# XXIV International Workshop on Deep-Inelastic Scattering and Related Subjects (DIS16)

Europe/Berlin
DESY Hamburg

#### DESY Hamburg

Notkestr. 85 D-22607 Hamburg Germany
Description

DIS2016 is the 24th in the series of annual workshops on Deep-Inelastic Scattering (DIS) and Related Subjects. The conference covers a large spectrum of topics in high energy physics. The programme is devoted to the most recent results from large experiments at CERN, DESY, BNL, FNAL, JLab, KEK, etc. and recent theoretical advances.

The programme is organised around seven working groups:
- Structure Functions and Parton Densities
- QCD and Hadronic Final States
- Electroweak Physics and Beyond the Standard Model
- Heavy Flavours (Charm, Beauty and Top)
- Small-x, Diffraction and Vector Mesons
- Spin Physics
- Future Experiments

The conference poster is available here.
Participants
• Abhay Deshpande
• Abilio De Freitas
• Achim Geiser
• Agnieszka Luszczak
• Agnieszka Oblakowska-Mucha
• Aharon Levy
• Aidan Robson
• Aiqiang Guo
• Alberto Accardi
• Alberto Orso Maria Iorio
• Aleksander Kusina
• Aleksandra Lelek
• Aleksei Ezhilov
• Alessia Bruni
• Alex Van Spilbeeck
• Alexander Khanov
• Alexander Kiselev
• Alexei Raspereza
• Alireza Aleedaneshvar
• Alireza Vafaee
• Allen Caldwell
• Amanda Cooper-Sarkar
• Ami Rostomyan
• Ana Sofia Nunes
• Andre Hoang
• Andrea Bressan
• Andreas Gellrich
• Andrew Papanastasiou
• Andrii Verbytskyi
• Annarita Buonaura
• Anton Karpishkov
• Antoni Szczurek
• Armando Bermúdez Martínez
• Artem Maevskiy
• Artur Trofymov
• Benoit Courbon
• Benoit Roland
• Bernd Surrow
• Bertrand Ducloue
• Bowen Wang
• Brian Foster
• Bryan Ramson
• Bugra Bilin
• CAPTAIN RITURAJ SINGH
• Carl Schmidt
• Carlos Marinas
• Carmen Diez Pardos
• Carsten Niebuhr
• Charlotte Van Hulse
• Christian Bierlich
• Christian Gumpert
• Christian Weiss
• Christian Wiese
• Christopher Dilks
• Claire Gwenlan
• Claudia Glasman
• Claudia Höhne
• Claudia Uebler
• Cynthia Keppel
• Daniel Britzger
• Daniel Buescher
• Daniel Hahne
• Daniel Tapia Takaki
• Daniel Troendle
• Daniela Dominguez Damiani
• Daniele Paolo Anderle
• Deepanwita Dutta
• Denis Bernard
• Deniz Poyraz
• Dieter Mueller
• Dirk Duschinger
• Djamel BOUMEDIENE
• Eckhard Elsen
• Elena Yatsenko
• Eleni Ntomari
• Elisa Fioravanti
• Elisabetta Gallo
• elke-caroline aschenauer
• Emanuele Roberto Nocera
• Emma Tolley
• Engin Eren
• Erin Seder
• Eva-MAria Kabuss
• Ewald Paul
• Fabrizio Caola
• Felix Socher
• Fengwangdong Zhang
• Fernanda Steffens
• Francesco Giovanni Celiberto
• Frank Tackmann
• Fredrick Olness
• Gabor Veres
• Ganna Dolinska
• Gary Goldstein
• Geert-Jan Besjes
• Gevorg Karyan
• Gianluca Inguglia
• Gilvan Alves
• Giuseppe Bevilacqua
• Grigorios Chachamis
• Guillermo Contreras
• Guillermo Gambini
• Halina Abramowicz
• Hamed BAKHSHIANSOHI
• Hang Yin
• Hannes Jung
• Hans Van Haevermaet
• Harleen Dahiya
• Harut Avagyan
• Hasib Ahmed
• Hayk Pirumov
• Heikki Mäntysaari
• Helena Santos
• Hua YE
• Iain Bertram
• Ievgen Korol
• Igor Katkov
• Ilkka Helenius
• Inti Lehmann
• Iris Abt
• Isabell Melzer-Pellmann
• J. Osvaldo Gonzalez Hernandez
• James Cockburn
• James Ferrando
• James Keaveney
• James Robinson
• Jan Kretzschmar
• Jasone Garay Garcia
• Jean-Philippe Lansberg
• Jennifer Thompson
• Jiayin Gu
• Jing Li
• Jiyeon Han
• Joachim Mnich
• Johannes Bellm
• John Dainton
• Jonathan Gaunt
• Joshua Davies
• Joël Feltesse
• Juan Rojo
• Juan Terron
• Judith Katzy
• Kai-Feng Chen
• Kalpana Bora
• Karel Cerny
• Karoly Urmossy
• Katarzyna Wichmann
• Katerina Lipka
• Katharina Müller
• Katie Graham
• Katja Krueger
• Kenta Yabe
• Kevin Black
• Kiyoshi Tanida
• Klaudia Burka
• Klaus Dehmelt
• Kollassery Swathi Sasikumar
• Konstantinos KORDAS
• Korinna Zapp
• Kyungseon Joo
• Laurent Favart
• Laurent Thomas
• Leszek Motyka
• Liang Zheng
• Lorenzo Sestini
• Luca Morescalchi
• Luca Rottoli
• Maarten Buffing
• Maciej Trzebinski
• Magdalena Slawinska
• Malte Wilfert
• Manaenkov Sergei
• Manfred Fleischer
• Marc Pelizaeus
• Marco Bonvini
• Maria Aldaya
• Mariaelena Boglione
• Mariola Klusek-Gawenda
• Marisa Sandhoff
• Markus Diefenthaler
• Markus Diehl
• Markus K. Koehler
• Marta Luszczak
• Marta Ruspa
• Martijn Mulders
• Mathias Butenschoen
• Matthew Wing
• Matthias Steinhauser
• Maxim Malyshev
• Maximilian Stahlhofen
• Michael Bender
• Michael Krämer
• Michael Rauch
• Mikhaylo Lisovyi
• Milena Quittnat
• Mirko Serino
• Mohamamd Kareem
• Mykola Savitskyi
• Márcia Quaresma
• Mélissa Ridel
• Naomi van der Kolk
• Nataliia Kovalchuk
• Nataliia Zakharchuk
• Nathan Hartland
• Nazar Bartosik
• Nisha Dhiman
• Nobuo Sato
• Norraphat Srimanobhas
• Olaf Behnke
• Oleksandr Viazlo
• Oleksandr Zenaiev
• Oleksii Turkot
• Olena Hlushchenko
• Or Hen
• Panagiotis Kokkas
• Paolo Gunnellini
• Patrick Connor
• Patrick Rieck
• Paul Newman
• Peter Schweitzer
• Philipp Joerg
• Pierre-Hugues Beauchemin
• Piet Mulders
• Pietro Marino
• Piotr Lebiedowicz
• Piotr Pietrulewicz
• Pouria Pedram
• Rafal Maciula
• Rainer Schicker
• Ralf Seidl
• Ram Krishna Dewanjee
• Ray Ling
• Renaud Boussarie
• Rene Angeles Martinez
• Riccardo Aliberti
• Rik Yoshida
• Ringaile Placakyte
• Robert Thorne
• Roberto Petti
• Rolf Ent
• Roman Kogler
• Ronan McNulty
• rosario nania
• Ruchi Chudasama
• Ryuma Hori
• Saeedeh Rostami
• Salvatore Fazio
• Sandra Kortner
• Sara Taheri Monfared
• Sebastien Kahn
• Sercan Sen
• Sergey Alekhin
• Sergey Baranov
• Sergey Kananov
• Sergey Kulagin
• Sergey Levonian
• Shima Shimizu
• Shinsuke Yoshida
• Silvia Niccolai
• Silvia Pisano
• Simon Plätzer
• Simon Spannagel
• Simone Alioli
• So Young Shim
• Soureek Mitra
• Spencer Klein
• Stamatios Gkaitatzis
• Stanislav Kazmin
• Stanislaw Mikocki
• Stefan Schmitt
• Stephan Thier
• Stephen Jones
• Sue Cheatham
• Suvarna Ramachandran
• Sven-Olaf Moch
• Svenja Pflitsch
• Tania Robens
• Thomas Gehrmann
• Thomas Peitzmann
• Tianbo Liu
• Tie-Jiun Hou
• Till Arndt
• Tom van Daal
• Tomas Davidek
• Tomasz Stebel
• Tomasz Szumlak
• Uri Karshon
• Valerio Bertone
• Victor Paulo Goncalves
• Volodymyr Myronenko
• Wally Melnitchouk
• William Schmidke
• Wim Cosyn
• Wolfgang Lukas
• Wolfgang Schaefer
• Xavier COUBEZ
• xiaoxuan chu
• Yajin Zhou
• Yogesh Kumar
• Yu Zhang
• Yuhong Zhang
• Yuji Koike
• Yusufu Shehu
• Yvonne Peters
• Zhiguo He
• Zoltan Nagy
Contact and questions
• Monday, April 11
• Plenary Auditorium

### Auditorium

#### DESY Hamburg

Notkestr. 85 D-22607 Hamburg Germany
Convener: Prof. John Dainton (Liverpool)
• 1
Conference opening
Speaker: Dr Olaf Behnke (DESY)
• 2
Parton Density Functions
Speaker: Pavel Nadolsky (Southern Methodist University)
• 3
The HERA Legacy
Speaker: Paul Newman (Birmingham University)
• 4
DESY director's Welcome
Speaker: Prof. Helmut Dosch (DESY)
• 10:35 AM
Coffee break
• Plenary Auditorium

### Auditorium

#### DESY Hamburg

Notkestr. 85 D-22607 Hamburg Germany
Convener: Prof. Amanda Cooper-Sarkar (Oxford University)
• 5
Speaker: Prof. Thomas Gehrmann (Universitaet Zuerich)
• 6
QCD at Colliders
Speaker: Dr Katharina Mueller (University of Zurich)
• 7
Low-x and Diffraction
Speaker: Laurent Favart (Brussels)
• 1:00 PM
Lunch break
• Plenary Auditorium

### Auditorium

#### DESY Hamburg

Notkestr. 85 D-22607 Hamburg Germany
Convener: Rolf Ent (Jefferson Lab)
• 8
Astro-particle Physics Review
Speaker: Dr Johannes Knapp (DESY)
• 9
Spin Physics
Speaker: Ralf Seidl (RIKEN)
• 3:50 PM
Conference Photo Foyer Auditorium

### Foyer Auditorium

#### DESY Hamburg

• 3:55 PM
Coffee break
• Plenary Auditorium

### Auditorium

#### DESY Hamburg

Notkestr. 85 D-22607 Hamburg Germany
Convener: Dr Eckhard Elsen (DESY)
• 10
Searches Landscape 2016
Speaker: Michael Krämer (Aachen)
• 11
Higgs and Electroweak results
Speaker: Sandra Kortner (MPI Munich)
• 12
Top Quark Results
Speaker: Orso Iorio (Napoli)
• 6:50 PM
Bus transfer to town hall - Buses leave DESY between 18:50 and 19:00
• 8:00 PM
Reception - Do not forget to bring your passport or national ID and the ticket (personal invitation) Town Hall

### Town Hall

#### DESY Hamburg

• 10:00 PM
Bus transfer to DESY, stop at Altona and Bahrenfelder Trabrennbahn
• Tuesday, April 12
• WG2 QCD and Hadronic Final States SR1

### SR1

#### DESY Hamburg

Notkestr. 85 D-22607 Hamburg Germany
Conveners: Frank Tackmann (DESY), Dr Shima Shimizu (Kobe University), Dr Simon Plätzer (DESY Theory Group)
• 13
• 14
Bose–Einstein correlations in hadron-pairs from lepto-production on nuclei ranging from hydrogen to xenon
Bose–Einstein correlations of like-sign charged hadrons produced in deep-inelastic electron and positron scattering are studied in the HERMES experiment using nuclear targets of 1H, 2H, 3He, 4He, N, Ne, Kr, and Xe. A Gaussian approach is used to parametrize a two-particle correlation function determined from events with at least two charged hadrons of the same sign charge. This correlation function is compared to two different empirical distributions that do not include the Bose–Einstein correlations. Clear signals of Bose–Einstein correlations for all target nuclei without a significant variation with the nuclear target mass are found. Also, no evidence for a dependence on the invariant mass W of the photon-nucleon system is found when the results are compared to those of previous experiments.
Speaker: Dr Gevorg Karyan (Yerevan Physics Institute)
• 15
Measurement of the ridge correlations in pp and pPb collisions with the ATLAS detector at the LHC
ATLAS measurement of azimuthal correlations between particle pairs at large pseudorapidity separation in pp and pPb collisions are presented. The data were collected using a combination of the minimum-bias and high track-multiplicity triggers. A detailed study of the dependence of two-particle correlations on the charged particle multiplicity, transverse momentum of the pair constituents and the pseudorapidity separation between particles forming a pair is shown. Measurements of multi-particle cumulants in the azimuthal angles of produced particles in wide pseudorapidity (|η|<2.5) and multiplicity ranges, with the aim to extract a single particle anisotropy coefficient, v1-v5, are also presented. These measurements can help to understand the origin of the long-range correlations seen in high-multiplicity pp and p+Pb collisions.
Speaker: Klaudia Burka (Polish Academy of Sciences)
• 16
Statistical Hadronisation in ep, ee, pp and AA Collisions
It has been shown that power-law hadron spectra observed in jets stemming from high-energy ee and pp collisions can be described by a statistical hadronisation model based on microcanonical statistics and superimposed Negative-Binomial (NBD) multiplicity fluctuations [1,2,3]. In this talk, applications of this model to ep DIS are discussed: fits to fragmentation functions and multiplicity distributions are presented. Besides, applications of such fragmentation model to heavy-ion collisions are also discussed based on [4,5]. Refs.: [1] Phys. Lett. B, 718 (2012) 125-129, arXiv:1204.1508 [2] Phys. Lett. B, 701 (2011) 111-116, arXiv:1101.3023 [3] Acta Phys.Polon.Supp. 5 (2012) 363-368 [4] Phys.Lett. B689 (2010) 14-17, arXiv:0911.1411 [5] J.Phys.Conf.Ser. 612 (2015) 1, 012048
Speaker: Karoly Urmossy (Shandong University, Jinan China; Wigner RCP Hungary)
• WG1 Structure Functions and Parton Densities Auditorium

### Auditorium

#### DESY Hamburg

Conveners: Dr Katarzyna Wichmann (DESY), Prof. Robert Thorne (University College London), Prof. Ronan McNulty (University College Dublin)
• 17
Update of MMHT PDFs
We present continuing work on the the MMHT PDFs. We discuss the changes in the PDFs and predictions due to variation in heavy quark masses. We present in detail the impact of the final combined HERA cross section data, and examine the fit quality. We also highlight plans for the future, in particular the potential impact of data sets not included in the current fit, and of new theoretical calculations.
Speaker: Prof. Robert Thorne (University College London)
• 18
Progress in the NNPDF global analysis
In this talk we present recent progress in the NNPDF global analysis, in particular work towards an updated NNPDF3.1 release. Recent developments include the inclusion of the combined HERA data and of several new LHC and Tevatron experiments, theoretical improvements such as the FONLL GM-VFN scheme with heavy quark masses, fits with heavy quark mass variations and with intrinsic charm, and updates in fitting methodology.
Speaker: Dr Juan Rojo (University of Oxford)
• 19
An investigation of the HERA combined data at low Q^2
In the HERAPDF2.0 PDF analysis it was noted that the fit $chi^2$ worsens significantly at low $Q^2$ for both NLO and NNLO fits. The turn over of the reduced cross section at low-$x$ and low $Q^2$ due to the contribution of the longitudinal cross section $F_L$ is also not very well described. In this paper the prediction for $F_L$ is highlighted and the corresponding extraction of $F_2$ from the data is further investigated, showing discrepancies with description of HERAPDF2.0 at low $x$ and $Q^2$. The effect of adding a simple higher twist term of the form ~constant/Q^2 to the description of $F_L$ is investigated. This results in a significantly better description of the reduced cross-sections, F2 and FL at low x, Q^2 and a significantly lower $\chi^2$ for the NNLO fit as compared to the NLO fit. This is not the case if the higher twist term is added to $F_2$.
Speakers: Prof. A. Cooper-Sarkar (Oxford), Prof. Amanda Cooper-Sarkar (Oxford), Prof. Amanda Cooper-Sarkar (Oxford University)
• 20
Dipole model analysis of the new HERA data
I analyse, within a dipole model, the inclusive DIS cross section data, obtained from the last HERA measurements (2015). I show that these high precision data are very well described within the dipole model framework, which is complemented with a valence quark structure functions. I also discuss the role of higher twist corrections to the standard PDFs fit. This analysis I have done in collaboration with Henri Kowalski and we are going to publish it soon.
Speakers: Dr Agnieszka Luszczak (Institute of Nuclear Physics), agnieszka luszczak (Cracow university)
• 21
Disussion
• WG3 Electroweak Physics and Beyond the Standard Model SR2

### SR2

#### DESY Hamburg

Conveners: Prof. Kevin Black (Boston University), Prof. Sanjay Padhi (Brown University), Prof. Shufang Su (University of Arizona)
• 22
Search for the 125 GeV Higgs Boson at 13 TeV in the diboson decay channels, by the ATLAS collaboration.
The ATLAS collaboration has searched for the Standard Model Higgs Boson in the first run-2 data using 3.2 fb^(-1) at 13 TeV. Results are presented in terms of central value and limits on the fiducial and total cross-sections.
• 23
Search for SM and MSSM dimuon Higgs decay channel with CMS
The search for the Higgs boson dimuon decay in standard model (SM) and its minimal supersymmetric extension (MSSM) based on the proton-proton collision data collected with the CMS detector at LHC is presented. To enhance the sensitivity of the search, events are categorised according to different production mechanisms and the dimuon invariant mass. Upper limits on the production cross section at 95% confidence level are reported for Higgs bosons masses in the range from 120 to 150 GeV for the SM search while for the MSSM case the mass range is extended from 115 to 300 GeV. An independent model search in the dimuon final state is also presented. The limits in the independent model search cover the mass range from 115 GeV to 500 GeV.
• 24
Search for the 125 GeV Higgs Boson produced in association with top quarks: final run-1 results and first run-2 results from the ATLAS collaboration.
The search for the production of the Higgs Boson with a pair of top-anti-top quarks is both very important and very challenging. The final results from run-1 are presented, with about 20 fb^(-1) of data at 8 TeV, as well as first run-2 results with 3.2 fb^(-1) of data at 13 TeV.
Speaker: Djamel Eddine Boumediene (Univ. Blaise Pascal Clermont-Fe. II)
• 25
Search for exotic and rare Higgs boson decays at CMS
Recent results on searches for exotic production and rare decays of the Higgs boson H(125) are presented. The current status of the searches for invisible and quasi invisible decays, decays to J/Psi+Gamma, and lepton flavour violation (emu, etau, mutau) decays of the boson will be reviewed, based on pp collision data collected at centre-­of-­mass energies of 7 and 8 TeV by the CMS collaboration at the LHC. Prospects will be given to extend these searches in the Run2 of the LHC.
Speaker: Mr Daniel Troendle (Uni Hamburg)
• WG4 Heavy Flavours SR3 (DESY, Hamburg)

### SR3

#### DESY, Hamburg

Conveners: Mr Martijn Mulders (CERN), Maximilian Stahlhofen (DESY), Mr Mikhaylo Lisovyi (DESY/Hamburg Uni)
• 26
DDbar and DD pair production at the LHCb in the parton Reggeization approach
We study the inclusive DDbar and DD pair production in proton-proton collisions at the LHC at leading order of the parton Reggeization approach endowed with universal scale-depended fragmentation functions for c-quark to D-meson and for gluon to D-meson transitions. We have described DDbar and DD correlations in azimuthal angle, as well as transverse momentum, rapidity, and invariant mass distributions measured in the forward region of rapidity by the LHCb Collaboration at the LHC (2 < y < 4) without free parameters. We have used Reggeized amplitudes for the processes RR->gg and RR->ccbar which are obtained accordingly to Feynman rules of the L.N. Lipatov effective theory of Reggeized partons, and Kimber-Martin-Ryskin model for unintegrated gluon distribution function in a proton with Martin-Stirling-Thorne-Watt collinear parton distributions as inputs.
Speaker: Mr Anton Karpishkov (Samara State Aerospace University)
• 27
New single- and double-parton scattering mechanisms for double charmed meson production
Some time ago two of us predicted that at large energies relevant for the LHC the production of double charm should be dominated by the double-parton scattering (DPS) mechanism [1]. Those studies of double $c \bar c$ production was extended next to the $k_t$-factorization approach which includes effectively higher-order QCD effects [2,3]. A relatively good description of the LHCb experimental data [4] was achieved for both the total yield and the dimeson correlation observables. The single-parton scattering (SPS) $g g \to c \bar c c \bar c$ contribution was discussed carefully in both collinear [3] and $k_t$-factorization [5] approaches. Their contribution to the $c \bar c c \bar c$ cross section was found to be rather small and was not able to describe details of the LHCb data. Here we discuss production of $D^0 D^0$ (and ${\bar D}^0 {\bar D}^0$) pairs within an alternative approach where $g \to D$ fragmentation is included [6]. We consider double-parton scattering (DPS) mechanisms of double $c \bar c$ production and subsequent $cc \to D^{0}D^{0}$ hadronization as well as double $g$ and mixed $g c\bar c$ production with $gg \to D^{0}D^{0}$ and $gc \to D^{0}D^{0}$ hadronization calculated with the help of the scale dependent hadronization functions of Kniehl et al. Single-parton scattering (SPS) mechanism of digluon production is also taken into account. We compare our results with several correlation observables in azimuthal angle $\varphi_{D^{0}D^{0}}$ between $D^{0}$ mesons or in dimeson invariant mass $M_{D^{0}D^{0}}$. The inclusion of new mechanisms with $g \to D^{0}$ fragmentation leads to larger cross sections, than when including only DPS mechanism with standard scale independent $cc \to D^{0}D^{0}$ fragmentation functions. Some consequences of the presence of the new mechanisms are discussed. In particular a larger $\sigma_{eff}$ is needed to describe the LHCb data. There is a signature that $\sigma_{eff}$ may depend on transverse momentum of $c$ quarks and/or $\bar c$ antiquarks. [1] M. Luszczak, R. Maciula and A. Szczurek, Production of two $c \bar c$ pairs in double-parton scattering, Phys. Rev. D 85, 094034 (2012). [2] R. Maciula and A. Szczurek, Production of $c \bar c c \bar c$ in double-parton scattering within $k_{t}$-factorization approach - meson-meson correlations, Phys. Rev. D 87, 074039 (2013). [3] A. van Hameren, R. Maciula and A. Szczurek, Single-parton scattering versus double-parton scattering in the production of two $c \bar c$ pairs and charmed meson correlations at the LHC, Phys. Rev. D 89, 094019 (2014). [4] R. Aaij et al. [LHCb Collaboration], Observation of double charm production involving open charm in pp collisions at $\sqrt{s}$ = 7 TeV, J. High Energy Phys. 06, 141 (2012); [J. High Energy Phys. 03, 108 (2014)]. [5] A. van Hameren, R. Maciula and A. Szczurek, Production of two charm quark-antiquark pairs in single-parton scattering within the $k_t$-factorization approach, Phys. Lett. B 748, 167 (2015). [6] R. Maciula and V. A. Saleev, A. V. Shipilova and A. Szczurek, arXiv:1601.06981 [hep-ph].
Speaker: Prof. Antoni Szczurek (the Institute of Nuclear Physics PAS)
• 28
Charm Physics at BESIII
The BESIII Experiment at the Beijing Electron Positron Collider (BEPCII) has accumulated the world's largest e+e- collision samples atψ(3770) peak, around theψ(4040) nominal mass, and at the Lambda_c-pair mass threshold which allow us to study decays of charmed mesons and baryons in a uniquely clean background. In this talk, we will review our recent results including: (1) the extractions of the D(s)+ decay constants, the form factors of D semi-leptonic decays, and the CKM matrix elements |Vcs(d)|; (2) the measurements of the strong phase and D0D0-bar mixing parameters using quantum coherence; (3) the determinations of the absolute branching fractions of the hadronic and semi-leptonic decays of Lambdac+.
Speaker: Yu Zhang (UCAS)
• 29
Measurements of CP violation in charm decays at LHCb
Most recent results on CP violation searches in the charm sector are presented. These include the world’s most precise measurements of direct and indirect CP asymmetries in the singly-Cabibbo-suppressed modes D0->pipi and D0->KK, based on the 3/fb data sample collected by LHCb during Run I.
Speaker: Mr Pietro Marino (SNS and INFN-Pisa)
• WG5 Small-x and Diffraction SR4b

### SR4b

#### DESY Hamburg

Conveners: Dr Alessia Bruni (INFN Bologna), Leszek Motyka (Jagiellonian University), Dr Rainer Schicker (Phys. Inst., Heidelberg)
• 30
The evolution of the virtual photon-proton cross section with coherence length
Assuming the form $\sigma^{\gamma P} \propto l^{\lambda_{\rm eff}}$ at fixed $Q^2$ for the behavior of the virtual-photon proton scattering cross section, where $l$ is the coherence length of the photon fluctuations, it is seen that the extrapolated values of $\sigma^{\gamma P}$ for different $Q^2$ cross for $l\approx 10^8$~fm. It is argued that this behavior is not physical, and that the behavior of the cross sections must change before this coherence length $l$ is reached. The behavior is compared to expectations to expectations from various models.
Speaker: Allen Caldwell (Max Planck Institute)
• 31
Sub-femtoscopic, Chromodynamic, Rutherford Scattering
Measurements of the lepto-production of vector mesons have always been pivotal in the development of a theory of hadron dynamics, challenging and elucidating the paradigm of the moment and thereby guiding our understanding of it to its present status in terms of QCD. Always with an experimentalist's appreciation of the momentous theoretical achievements of more recent years with QCD in mind, first steps in yet another new look at the measurements of such electro-production from the HERA ep collider is shown to provide simple and instructive insight in terms of what is truly chromodynamic Rutherford scattering within the dimension of confinement. The nature of further analysis of presently available data and the opportunities for progress in hadron dynamics in such terms with higher statistical sensitivity are mentioned.
Speaker: Prof. John Dainton (Cockcroft)
• 32
Next-to-leading order Balitsky-Kovchegov equation with resummation
The Color Glass Condensate framework has been successfully applied to many high-energy scattering processes, and it has also been seen as a powerful tool to describe initial state of heavy ion collisions. An important next step for the CGC phenomenology is to perform these calculations at next-to-leading order accuracy, which would allow a qualitative test of the saturation picture. A necessary ingredient in these calculations is the solution to the CGC evolution equation, the Balitsky-Kovchegov (BK) equation, at NLO accuracy. In our previous work [1] it was shown that the NLO BK equation is unstable and results in an unintegrated gluon distribution to decrease as momentum fraction x decreases. It could also drive the dipole amplitude to become negative even with physically relevant initial conditions. We show that when large single and double logarithmic corrections [2,3] are resumed in the equation, the evolution becomes stable and a physical solution is obtained. We determine the optimal way to include a maximal amount of full NLO result in the resummation by fixing the constant under the resummed large transverse logarithm. By direct numerical solution we show that the as^2 terms that are not enhanced by large logarithms can be neglected at large saturation scales (late in the evolution). However, these numerically demanding terms have a significant effect close to phenomenologically relevant initial conditions. The NLO evolution obtained in this work should be suitable for phenomenological calculations with NLO cross sections. The work presented in this talk is published in [4]. References [1] T. Lappi and H. Mäntysaari, Direct numerical solution of the coordinate space Balitsky-Kovchegov equation at next to leading order, Phys. Rev. D91 (2015) [arXiv:1502.02400 [hep-ph]] [2] E. Iancu, J. D. Madrigal, A. H. Mueller, G. Soyez and D. N. Triantafyllopoulos, Resumming double logarithms in the QCD evolution of color dipoles, Phys. Lett. B744 (2015) 293 [arXiv:1502.05642 [hep-ph]]. [3] E. Iancu, J. D. Madrigal, A. H. Mueller, G. Soyez and D. N. Triantafyllopoulos, Collinearly-improved BK evolution meets the HERA data, arXiv:1507.03651 [hep-ph]. [4] T. Lappi, H. Mäntysaari, Next-to-leading order Balitsky-Kovchegov equation with resummation. arXiv:1601.06598
Speaker: Dr Heikki Mäntysaari (Brookhaven National Laboratory)
• 33
NLO impact factor for diffractive dijet production in the shockwave formalism
We present the computation for the impact factor for the production of dijets in diffractive DIS at Next-to-Leading Order using Balitsky's shockwave formalism.
Speaker: Renaud Boussarie (CNRS, Univ. Paris-Sud, 91405 Orsay, France)
• WG6 Spin Physics SR4a

### SR4a

#### DESY Hamburg

Conveners: Dr Emanuele Roberto Nocera (Rudolf Peierls Centre for Theoretical Physics University of Oxford), Dr Erin Seder (CEA Saclay DSM/IRFU/SPhN/LSN), Dr Salvatore Fazio (Brookhaven National Laboratory), Dr Silvia Pisano (Laboratori Nazionali di Frascati - INFN)
• 34
Gluon transverse momentum dependent correlators in polarized high energy processes
We investigate the gluon transverse momentum dependent correlators as Fourier transform of matrix elements of nonlocal operator combinations. At the operator level these correlators include both field strength operators and gauge links bridging the nonlocality. In contrast to the collinear PDFs, the gauge links are no longer unique for transverse momentum dependent PDFs (TMDs) and also Wilson loops lead to nontrivial effects. We look at gluon TMDs for unpolarized, vector and tensor polarized targets. In particular a single Wilson loop operators become important when one considers the small-x limit of gluon TMDs.
Speaker: Piet Mulders (Nikhef and VU, Amsterdam)
• 35
Perturbative QCD, resummation and non-perturbative aspects in SIDIS processes
I will address the study of semi-inclusive deep inelastic scattering cross sections as functions of the transverse momentum, $q_T$. Soft gluon resummation is performed using the original Collins-Soper-Sterman (CSS) formalism or, equivalently, the improved Transverse Momentum Dependent (TMD) framework. The focus of this talk is the matching between the region where fixed order perturbative QCD can successfully be applied and the region where soft gluon resummation is necessary. Interestingly, the commonly used prescription of matching through the so-called Y-factor cannot be applied, at least in the SIDIS kinematical configurations considered. In particular, the non-perturbative component of the resummed cross section turns out to play a crucial role and should not be overlooked even at relatively high energies. Moreover, I will show the theoretical uncertainties of the transverse momentum resummed cross sections in the CSS formalism related to the scale parameters C_1, C_2 and C_3, and their interplay with the uncertainties of the non perturbative parameters g_1, g_2 and g_3.
Speaker: Dr Mariaelena Boglione (University of Turin (Italy))
• 36
New pole contribution to transverse-momentum-weighted single-transverse spin asymmetry in semi-inclusive deep inelastic scattering
In this talk, we discuss the new hard pole contribution to the transverse-momentum-weighted single-transverse spin asymmetry in semi-inclusive deep inelastic scattering. We perform the complete next-to-leading order calculation of the $P_{h\perp}$-weighted cross section and show that the new hard pole contribution is required in order to obtain the complete evolution equation for the Qiu-Sterman function derived by different approaches.
Speaker: Dr Shinsuke Yoshida (Central China Normal University)
• 37
Tagged spectator DIS off a polarized spin-1 target
We cover the general structure of the SIDIS cross section with a polarized beam and spin-1 target. The cross section is characterized by 41 structure functions of which 23 are unique to the spin-1 target case. Next, we study a specific example, namely DIS off a polarized deuteron with a slow detected nucleon in the final state ("tagged spectator DIS"). The reaction is studied in the impulse approximation using the virtual nucleon approximation. In these approximations, 25 structure functions are non-zero (16 of which are sensitive to the deuteron tensor polarization). Finally, we discuss possibilities of measurements of the structure functions at JLab12 and an EIC and their sensitivity to neutron structure functions.
Speaker: Prof. Wim Cosyn (Ghent University)
• 10:30 AM
Coffee break
• WG1 Structure Functions and Parton Densities Auditorium

### Auditorium

#### DESY Hamburg

Conveners: Dr Katarzyna Wichmann (DESY), Prof. Robert Thorne (University College London), Prof. Ronan McNulty (University College Dublin)
• 38
Beyond CT14: Hera 2 data, special PDF sets and more
We discuss recent activities of the CT global analysis group. This includes an update of CT14 to include the HERA1+2 combined data set, discussion of CT14 special sets such as CT14QED, intrinsic charm or asymmetric strange studies, and other current analyses based on CT14.
Speaker: Carl Schmidt (Michigan State University)
• 39
The new ABM16 PDFs
A new update of the ABM PDFs is presented, which, among other data, includes the new combined HERA DIS data from run II.
Speakers: Sergey Alekhin (UHH), Dr Sergey Alekhin (Institute for High Energy Physics (Protvino, Russia)), Dr Sergey Alekhin (Universität Hamburg), Sergey Alekhin (DESY)
• 40
The CJ15 PDFs
We present a new set of leading twist parton distribution functions, referred to as “CJ15”, which take advantage of developments in the theoretical treatment of nuclear corrections as well as new data. The analysis includes for the first time data on the free neutron structure function from Jefferson Lab and new high-precision charged lepton and W -boson asymmetry data from Fermilab. These significantly reduce the uncertainty on the d/u ratio at large values of x and provide new insight on the partonic structure of bound nucleons.
Speaker: Alberto Accardi (Hampton U. and Jefferson Lab)
• 41
The PDF4LHC 2015 recommendations for Run II
We present an updated recommendation for the usage of sets of parton distribution functions at the LHC Run II. We propose a new prescription for the combination of a suitable subset of the available PDF sets, which is presented in terms of a single combined PDF set. We discuss tools which allow for the delivery of this combined set in terms of optimized sets of Hessian eigenvectors or Monte Carlo replicas, and their usage, and provide some examples of their application to LHC phenomenology, with particular emphasis on the implications of the PDF4LHC15 combined sets Higgs physics.
Speaker: Dr Juan Rojo (University of Oxford)
• 42
PDF4LHC recommendations for LHC Run II: A critical appraisal
We review the current status in the determination of parton distribution functions in view of the precision requirements for LHC in the run II.
Speaker: Mrs Ringaile Placakyte (DESY)
• 43
Discussion
• WG2 QCD and Hadronic Final States SR1

### SR1

#### DESY Hamburg

Conveners: Frank Tackmann (DESY), Dr Shima Shimizu (Kobe University), Dr Simon Plätzer (DESY Theory Group)
• 44
Jet measurements in p+Pb and Pb+Pb with the ATLAS Experiment at the LHC
Jets provide a powerful tool for probing the dynamics of the quark-gluon plasma created in Pb+Pb collisions at the LHC. The modification of high-pT jets as they propagate in the quark-gluon plasma provides insight on structure of the plasma at short-length scale. Such modifications have been observed in a variety of measurements of single jet, dijet, photon-jet and charged-particle fragmentation functions. Recent results of modifications of jets in proton-lead and Pb+Pb collisions will be presented.
Speaker: Dr Helena Santos (LIP - Lisboa)
• 45
Understanding Jets in HI Collisions
Review of MC for heavy ions.
Speaker: Dr Korinna Zapp (CERN)
• 46
Measurement of photon production cross sections with the ATLAS detector
The production of prompt isolated photons at hadron colliders provides a stringent test of perturbative QCD and can be used to probe the gluon density function of the proton. The ATLAS collaboration has performed precise measurements of the inclusive production of isolated prompt photons in 20.3 /fb of data collected at a center-of-mass energy of 8TeV and in 3.2 /fb of data collected at a center-of-mass energy of 13TeV, differential in both rapidity and the photon transverse momentum. The measurements are compared with state-of-the-art theory predictions at NLO in QCD and with predictions of several MC generators. If available, further detailed studies of isolated photons and hadronic jets in the 8 TeV data set will be presented. These measurements were carried out in final states with at least one, two or three hadronic jets differential in a wide range of kinematic variables describing the photon+jet production dynamic. Colour-coherence effects were investigated in events with a photon accompanied by two jets. If available, further studies of production of pairs of isolated photons in the 8 TeV data set will be presented. These measurements are the most precise to data and were carried out both integrated and differential in a wide range of kinematic variables.
• 47
Prompt photon production in deep inelastic scattering at HERA
Following earlier measurements of prompt photon production in DIS, the ZEUS collaboration at HERA presents measurements of new kinematic variables. These include the azimuthal separations of the recoil electron, the outgoing photon and an accompanying jet, and the fraction of the incoming virtual photon energy that is taken by the outgoing photon and the jet.
Speaker: Ms Olena Hlushchenko (ZEUS, qcd working group)
• 48
Charged-Current Deep Inelastic Scattering at Third Order
For Deep Inelastic neutrino-proton scattering in the combination $\nu P - \bar{\nu} P$, we compute the exact $\mathcal{O}(\alpha_s^3)$ perturbative QCD corrections to the charged-current structure functions $F_2$, $F_L$ and $F_3$. These results supersede previous approximations based on the first few Mellin moments by providing all-$N$ expressions for the coefficient functions. We discuss the numerical size of the third-order corrections and their behaviour in the threshold and high-energy limits.
Speaker: Mr Joshua Davies (University of Liverpool)
• WG3 Electroweak Physics and Beyond the Standard Model SR2

### SR2

#### DESY Hamburg

Conveners: Dr Alexis Kalogeropoulos (DESY), Prof. Kevin Black (Boston University)
• 49
Search for squark and gluino production in hadronic final states
Weak scale supersymmetry is one of the best motivated and studied extensions of the Standard Model. The recent increase in the center of mass energy of the proton-proton collisions gives a unique opportunity to extend the sensitivity to production of supersymmetric particles at the Large Hadron Collider. This talk summarises recent ATLAS results on searches for supersymmetric squarks and gluinos, including third generation squarks produced directly or via decay of gluinos. The searches involved final states containing jets (possibly identified as coming from b-quarks), missing transverse momentum and no leptons.
Speaker: Geert Jan Besjes (University of Copenhagen)
• 50
Search for squark and gluino production in leptonic final states
Weak scale supersymmetry is one of the best motivated and studied extensions of the Standard Model. The recent increase in the center of mass energy of the proton-proton collisions gives a unique opportunity to extend the sensitivity to production of supersymmetric particles at the Large Hadron Collider. This talk summarises recent ATLAS results on searches for supersymmetric squarks and gluinos, including third generation squarks produced directly or via decay of gluinos. The searches involved final states containing jets (possibly identified as coming from b-quarks), missing transverse momentum and leptons.
Speaker: Sebastien Jonathan Kahn (Centre National de la Recherche Scientifique Marseille)
• 51
Search for SUSY in jets+ MET final state
The results of inclusive searches for supersymmetry with all-hadronic events produced in proton-proton collision at 13 TeV are summarized. The data sample corresponds to an integrated luminosity of 2.3 fb-1 collected in 2015. The searches are based on jet multiplicity, bottom-quark jet multiplicity, and variables characterizing total event energy and missing transverse momentum. The results are interpreted in models of gluino pair production
Speaker: Bibhuprasad Mahakud (Tata Institute of Fundamental Research-A in Mumbai, India)
• 52
Search for production of SUSY particles produced via electroweak interactions
Many supersymmetry models feature gauginos and also sleptons with masses less than a few hundred GeV. These can give rise to direct pair production rates at the LHC that can be observed in the data sample recorded by the ATLAS detector. The talk summarises the status of searches for gaugino and slepton pair production in final states with leptons.
Speaker: Ciwake Shehu (University of Sussex)
• 53
Electroweak production of SUSY in diTau final states
A search for electroweak production of supersymmetric particles is performed with two tau leptons in the final state. These results are based on 18.1 to 19.6 fb$^{-1}$ of proton-proton collisions at $\sqrt{s}$ = 8\TeV collected with the CMS detector at the CERN Large Hadron Collider. The observed events are found to be consistent with the standard model prediction. Upper limits are set on the masses of the lightest chargino and the lightest neutralino, assuming the third generation sleptons are the lightest sleptons and their masses are at a middle point between the chargino and the neutrralino.
Speaker: Hamed Bakhshiansohi (Institute for Studies in Theoretical Physics & Mathematics (IPM) in Tehran, Iran)
• 54
Search for R-parity violating or long-living SUSY particles
The proton-proton collisions at sqrt{s} = 13 TeV at the LHC have increased the ATLAS sensitivity to production of strongly produced supersymmetric particles. If R-parity is not conserved, these particles may decay to jets and leptons, and lightest supersymmetric particles may decay into many leptons with or without missing transverse momentum. Several supersymmetric models also predict massive long-lived supersymmetric particles. Such particles may be detected through abnormal specific energy loss, appearing or disappearing tracks, displaced vertices, long time-of-flight or late calorimetric energy deposits. The talk presents recent results from searches of supersymmetry in resonance production, R-parity violating signatures and events with long-lived particles with the ATLAS detector using LHC Run 2 data.
Speaker: Bradley Dean Axen (Lawrence Berkeley National Lab.)
• WG4 Heavy Flavours SR3 (DESY, Hamburg)

### SR3

#### DESY, Hamburg

Conveners: Mr Martijn Mulders (CERN), Maximilian Stahlhofen (DESY), Mr Mikhaylo Lisovyi (DESY/Hamburg Uni)
• 55
Recent BABAR results on charmed mesons
Based on the full data set recorded with the BABAR detector at center-of-mass energies at and near the Upsilon(4S) resonance, and corresponding to an integrated luminosity of approximately 468 fb-1, we measure the D0-D0bar mixing parameters using a time-dependent amplitude analysis of the decay D0 -> pi+pi-pi0. With the same BABAR data set, we also measure the mass difference, Delta m, between the D*(2010)+ and the D+ using the decay chain D*(2010)+ -> D+ pi0 with D+ -> K- pi+ pi+. We additionally combine this result with a previous BABAR measurement of m(D*(2010)+) - m(D0) and obtain results that are approximately seven times more precise than the present world averages.
Speaker: Adrian John Bevan (Queen Mary University of London)
• 56
Mixing and CP-violation in the Bd and Bs systems
Search for deviations from the standard model is performed in the systems of the neutral B mesons. The Bs system is studied in the decay into J/psi phi. The mixing phase phi_s and the width difference DeltaGamma_s are determined through the simultaneous study of angular distributions in the final state and of the decay time, performed together with flavor tagging at production. ÊThe measurement performed by ATLAS with the full LHC Run-1 sample is discussed and compared to the previous world average. The width difference DeltaGamma_d in the Bd system is obtained from the comparison of the decay time distributions in the flavor specific state J/psi K* and in the CP eigenstate J/psi KS. The result obtained from the full sample of data collected by ATLAS at 7 and 8 TeV is the most accurate single measurement of the width difference currently available.
• 57
Results of radiative and annihilation penguin decays at Belle
We present the results of radiative and annihilation penguin $B(B_{s})$ decays at Belle. The $b\rightarrow s (d)\gamma$ processes are sensitive to physics beyond the Standard Model as new heavy particles can enter the loop and change the branching fractions and/or the kinematic variables. We report the results of fully inclusive $B\rightarrow X_{s,d}\gamma$ decay with both leptonic tagging and hadronic tagging methods. We also report the results of the exclusive decays $B(B_{s})\rightarrow \phi\gamma$ and $B_{s}\rightarrow \gamma\gamma$.
Speaker: Dr Deepanwita Dutta (Tata Institute of Fundamental Research)
• 58
Search for new physics in rare and semi-rare decays of B-mesons
Processes involving the FCNC transitions in b-hadron decays are suppressed in the SM and are sensitive to new physics. New results in the search for the rare decays of Bs and Bd into mu+mu- are presented. They are based on the full sample of data collected by ATLAS at 7 and 8 TeV of collision energy. The consistency with the SM and with other available measurements is discussed. The properties of the decay of the Bd meson into K*mu+mu- are relevant because of possible deviations from the standard model observed by LHCb. We present recent results obtained by ATLAS, concerning the angular distribution parameters FL, S_i and P_i in the region Q^2(mu+mu-)<6 Gev^2,
Speaker: Adrian John Bevan (London QUML)
• 59
Recent results on Bc properties and decays from LHCb
Precision measurements of the Bc mass, lifetime and relative production cross-section, and the observation of several new decay modes were achieved using the 3 fb-1 of data collected by the LHCb experiment during the first run of the LHC. These results provide useful input for QCD effective models.
Speaker: Dr Hang Yin (Central China Normal Univerisity)
• WG5 Small-x and Diffraction SR4b

### SR4b

#### DESY Hamburg

Conveners: Dr Alessia Bruni (INFN Bologna), Leszek Motyka (Jagiellonian University), Dr Rainer Schicker (Phys. Inst., Heidelberg)
• 60
Incoherent diffraction and structure fluctuations at small x
Exclusive vector meson production can be used to directly probe the gluon density of a hadron. Measuring the cross section differentially in the momentum transfer t makes it possible to determine the transverse density profile (via coherent diffraction) and density fluctuations (incoherent diffraction) of the target hadron. This knowledge on the geometric fluctuations of the proton is particularly important for understanding collective phenomena observed in proton-nucleus collisions. We calculate coherent and incoherent diffractive vector meson production in photon-proton and photon-nucleus scattering. The dipole model used in the calculation is constrained by the proton structure function data. By implementing sub-nucleon scale fluctuations using the constituent quark model or the IP-glasma framework we demonstrate that incoherent gamma-p scattering is sensitive to small-scale fluctuations. We discuss to what extent the current HERA diffractive deep inelastic scattering data can be used to constrain the proton structure fluctuations and how an Electron Ion Collider (EIC) can improve the picture. Before an EIC, the only processes that can be used to study diffraction with nuclear targets at high energy are ultraperipheral heavy ion collisions. We present an updated CGC calculation where a dipole model constrained by more precise combined HERA structure function data is used, and calculate diffractive cross sections at sqrt(s)=5 TeV. We discuss how access to the ultraperipheral cross section at different energies can help to study the nuclear wave function and its fluctuations.
Speaker: Dr Heikki Mäntysaari (Brookhaven National Laboratory)
• 61
Measurement of the cross-section ratio sigma(psi(2S))/sigma(J/psi(1S)) in deep inelastic exclusive ep scattering at HERA
The exclusive deep inelastic electroproduction of psi(2S) and J/\psi(1S) at an ep centre-of-mass energy of 317 GeV has been studied with the ZEUS detector at HERA in the kinematic range 2 < Q2 < 80 GeV2, 30 < W < 210 GeV and |t| < 1 GeV2, where Q2 is the photon virtuality, W is the photon--proton centre-of-mass energy and t is the squared four-momentum transfer at the proton vertex. The data for 2 < Q2 < 5 GeV2 were taken in the HERA I running period and correspond to an integrated luminosity of 114 pb-1. The data for 5 < Q2 < 80 GeV2 are from both HERA I and HERA II periods and correspond to an integrated luminosity of 468 pb-1. The decay modes analysed were mu+ mu- and J/psi(1S) pi+ pi- for the psi(2S) and mu+ mu- for the J/psi(1S). The cross-section ratio sigma(psi(2S))/sigma(J/psi(1S)) has been measured as a function of Q2, W, and t. The results are compared to predictions of QCD-inspired models of exclusive vector-meson production.
Speaker: Ms Nataliia Kovalchuk (UNI/EXP CMS)
• 62
AdS/QCD predictions for diffractive $\phi$ meson production
We use the holographic light front wavefunction for the $\phi$ meson obtained from AdS/QCD, in conjunction with the Color Glass Condensate dipole cross-section whose parameters are fitted to the most recent precise combined HERA data on inclusive Deep Inelastic Scattering, to compute the rate for diffractive $\phi$ electro-production. Our predictions are in good agreement with the available data collected at the HERA collider.
• 63
Exclusive &rho;0 Meson Photoproduction with a Leading Neutron at HERA
A first measurement is presented of exclusive photoproduction of ρ0 mesons associated with leading neutrons at HERA. The data were taken with the H1 detector in the years 2006 and 2007 at a centre-of-mass energy of √=319 GeV and correspond to an integrated luminosity of 1.16 pb-1. The ρ0 mesons with transverse momenta p_T<1 GeV are reconstructed from their decays to charged pions, while leading neutrons carrying a large fraction of the incoming proton momentum, x_L>0.35, are detected in the Forward Neutron Calorimeter. The phase space of the measurement is defined by the photon virtuality Q2<2 GeV2, the total energy of the photon-proton system 20<W<100 GeV and the polar angle of the leading neutron θ_n<0.75 mrad. The cross section of the reaction γp → ρ0 n π+ is measured as a function of several variables. The data are interpreted in terms of a double peripheral process, involving pion exchange at the proton vertex followed by elastic photoproduction of a ρ0 meson on the virtual pion. In the framework of one-pion-exchange dominance the elastic cross section of photon-pion scattering, σ_el(γπ+ → ρ0π+), is extracted. The value of this cross section indicates significant absorptive corrections for the exclusive reaction studied.
Speaker: Dr Sergey Levonian (DESY)
• 64
Inclusive and exclusive processes with a leading neutron in ep collisions
The color dipole formalism is extended to the study of exclusive processes associated with a leading neutron in ep collisions at high energies. We discuss the leading neutron production in $e + p \rightarrow e + n + X$ collisions at high energies and estimate the related observables, which were measured at HERA and may be analysed in future electron-proton ($ep$) colliders. We show that the recently released H1 leading neutron spectra can be reproduced using the color dipole formalism and that these spectra could help us to observe more clearly gluon saturation effects in future ep colliders. Moreover, the exclusive $\rho$, $\Phi$ and $J/\Psi$ production, as well as the Deeply Virtual Compton Scattering, are analysed assuming a diffractive interaction between the color dipole and the pion emitted by the incident proton. We compare our predictions with the HERA data on $\rho$ production and estimate the magnitude of the absorption corrections. We show that the color dipole formalism is able to describe the current data. Finally, we present our estimate for the exclusive cross sections which can be studied at HERA and in future electron-proton colliders.
Speaker: Prof. Victor Paulo Goncalves (Lund University)
• WG6 Spin Physics SR4a

### SR4a

#### DESY Hamburg

Conveners: Dr Emanuele Roberto Nocera (Rudolf Peierls Centre for Theoretical Physics University of Oxford), Dr Erin Seder (CEA Saclay DSM/IRFU/SPhN/LSN), Dr Salvatore Fazio (Brookhaven National Laboratory), Dr Silvia Pisano (Laboratori Nazionali di Frascati - INFN)
• 65
Single spin asymmetries of forward neutron production in polarized p+p and p+A collisions at sqrt(s)=200 GeV
In high-energy hadron collisions, most energy goes into the forward region. However, particle production mechanisms in the forward region are not well understood as perturbative QCD is not applicable at small momentum transfers. We study single spin asymmetries (A_N) of forward neutron production in the PHENIX experiment using a transversely polarized proton beam. In 2015, we took data for p + A collisions for the first time with Au and Al beams at sqrt(s_NN)= 200 GeV and observed a surprising A dependence. The results will be presented in the conference together with discussions on possible mechanisms that could explain the A_N results of forward neutron production.
Speaker: Dr Kiyoshi Tanida (Japan Atomic Energy Agency)
• 66
Measurement of Transverse Single Spin Asymmetries in $\pi^0$ Production from $p^{\uparrow}+p$ and $p^{\uparrow}+A$ Collisions at STAR
In 2015 the first collisions between polarized protons and nuclei occurred at the Relativistic Heavy Ion Collider (RHIC), at a center-of-mass energy of $\sqrt{s_{NN}}=200$ GeV. Comparisons between spin asymmetries and cross-sections in $p+p$ production to those in $p+A$ production provide insight into nuclear structure, namely nuclear modification factors, nuclear dependence of spin asymmetries, and comparison to models with saturation effects. The transverse single spin asymmetry, $A_N$, has been measured in $\pi^0$ production in the STAR Forward Meson Spectrometer (FMS), an electromagnetic calorimeter covering a forward psuedorapidity range of $2.6<\eta<4$. Within this kinematic range, STAR has previously reported the persistence of large $\pi^0$ asymmetries with unexpected dependences on $p_T$ and event topology in $p+p$ collisions. This talk will compare these dependences to those in $p+A$ production.
Speaker: Mr Christopher Dilks (Pennsylvania State University)
• 67
Transverse single-spin asymmetry of weak bosons and Drell-Yan production in p+p collisions at STAR: present and future
Accessing the Sivers TMD function in proton+proton collisions through the measurement of transverse single spin asymmetries (TSSAs) in Drell-Yan and weak boson production is an effective path to test the fundamental QCD prediction of the non-universality of the Sivers function. Furthermore, it provides data to study the spin-flavor structure of valence and sea quarks inside the proton and to test the evolution of parton distributions. The TSSA amplitude, $A_{N}$, has been measured at STAR in proton+proton collisions at $\sqrt{s} = 500$~GeV, with a recorded integrated luminosity of $25~\text{pb}^{-1}$. Within relatively large statistical uncertainties, the current data favor theoretical models that include change of sign for the Sivers function relative to observations in SIDIS measurements, if TMD evolution effects are small. RHIC plans to run proton+proton collisions of transversely polarized beams at $\sqrt{s} = 510$~GeV in 2017, delivering an integrated luminosity of $400~\text{pb}^{-1}$. This will allow STAR to perform a precise measurement of TSSAs in both Drell-Yan and and weak boson production. The present status and future plans for the Sivers function program at STAR will be discussed as well as other observables sensitive to the non-universality of the Sivers function via Twist-3, e.g. the TSSA of direct photons.
Speaker: Dr Salvatore Fazio (Brookhaven National Laboratory)
• 68
Correlations in back-to-back hadron production in SIDIS
Speaker: Harut Avagyan (JLab)
• 69
Azimuthal distributions in unpolarized SIDIS
Studies of spin-azimuthal asymmetries in semi-inclusive production of hadrons have been widely recognized as key objectives of the JLab 12 GeV upgrade and a driving force behind the construction of the Electron Ion Collider. Various assumptions involved in preliminary extraction of underlying transverse momentum dependent partonic distributions (TMDs) from available data, have yet to allow credible estimates of systematic errors associated with those assumptions. One of the challenges in extraction of underlying transverse momentum dependent partonic distributions from precision measurements of hard scattering processes is the clear understanding of the QCD fundamentals of quark-gluon correlations and higher twist effects. In recent years it became clear, that observables which are constructed by taking ratios are not ideal grounds for studies of TMDs, and in particular transverse momentum of TMDs and their evolution effects, which are the most intriguing part of 3D non-perturbative partonic distributions. The high-statistics data samples from HERMES and COMPASS collaborations have been used in phenomenological analyses to extract information on the flavor dependence of unpolarized TMD distribution and fragmentation functions. The hadron multiplicities study is now being extended to a multi-dimensional analysis, in particular looking to the transverse momentum dependence and its correlations with other kinematic variables, including the azimuthal angle between lepton scattering and hadron production planes. In this contribution we present recent studies of azimuthal dependences of charged pion distributions in SIDIS using the CLAS data at 5.5 GeV, and comparison with measurements performed at higher energy by the HERMES collaboration.
Speaker: Harut Avagyan (JLab)
• 70
Transverse-momentum dependent semi-inclusive deep-inelastic scattering at HERMES
Semi-inclusive deep-inelastic lepton-nucleon scattering provides a powerful tool for unraveling the multi-dimensional internal spin-momentum structure of the nucleon. In particular, the dependence on transverse momentum of the produced hadron allows the study of numerous novel effects like the Sivers and Collins mechanism. The HERMES experiment, with its versatile gas target internal to the HERA lepton storage ring, had taken data with various polarized and unpolarized nuclear-polarized gas targets. Results are presented on the azimuthal distribution of identified hadrons (pions, kaons, and protons) from scattering longitudinally polarized leptons by unpolarized protons and deuterons as well as from scattering both unpolarized and longitudinally polarized leptons by transversely polarized protons. Emphasis is given on the multi-dimensional dependences of these single- and double-spin asymmetries.
Speaker: Ms Charlotte Van Hulse (University of the Basque Country)
• 1:00 PM
Lunch break
• WG2 QCD and Hadronic Final States SR1

### SR1

#### DESY Hamburg

Conveners: Frank Tackmann (DESY), Dr Shima Shimizu (Kobe University), Dr Simon Plätzer (DESY Theory Group)
• 71
Search for QCD Instanton-Induced Processes in DIS at HERA
Signals of QCD instanton-induced processes are searched for in deep-inelastic scattering (DIS) at the electron-proton collider HERA in the kinematic region defined by the Bjorken-scaling variable x > 0.001, the inelasticity 0.2< y < 0.7 and the photon virtuality 150 < Q2 < 15000 GeV^2. The search is performed using H1 data corresponding to an integrated luminosity of 350 pb^-1. Several observables of the hadronic final state of the events are exploited to identify a potentially instanton-enriched domain. Two Monte Carlo models, RAPGAP and ARIADNE, are used to estimate the background from the standard DIS processes, and the instanton-induced scattering processes are modeled by the program QCDINS. In order to extract the expected signal a multivariate data analysis technique is used. Exclusion limits on instanton production are reported, excluding cross sections larger than 2 pb. Limits are also reported as a function of parameters used to regularize the perturbative instanton model.
Speaker: Stanislav Mikocki (Institute of Nuclear Physics Polish Academy of Sciences)
• 72
The BESIII experiment at the electron positron collider BEPCII in Beijing is successfully operating since 2008 and has collected large data samples in the tau-mass region, including the world’s largest data samples at the J/ψandψ(2S) resonances. In particular decays of these two resonances provide a rich and clean environment to study hadrons consisting out of light quarks and search for exotics. The BESIII collaboration has recently started a campaign to understand the nature of the X(1835) and Y(2175) resonances, which are debated to be exotic matter. Further, decays of eta’ mesons are studied to deepen our knowledge of their structure and possible symmetry breaking effects in their decays. In this presentation recent results of the light hadron physics program will be highlighted.
Speaker: Dr Marc Pelizaeus (Ruhr-University Bochum)
• 73
Search for a narrow baryonic state decaying to pKS0 and \bar{p}KS0 in deep inelastic scattering with the HERA II data
A search for a narrow baryonic state in the pKS0 and \bar{p}KS0 system has been performed in ep collisions at HERA with the ZEUS detector using an integrated luminosity of 358 pb−1 taken in 2003-2007. The search was performed with deep inelastic scattering (DIS) events at an ep centre-of-mass energy of 318 GeV for exchanged photon virtuality, Q2, between 20 and 100 GeV2. Contrary to evidence presented for such a state around 1.52 GeV in a previous ZEUS analysis using a sample of 121 pb−1, taken in 1995–2000, no resonance peak is found in the p(\bar{p})KS0 invariant-mass distribution in the range 1.45–1.7 GeV. Upper limits on the production cross section are set for different assumptions on the width of the resonance.
Speaker: Mr Ryuma Hori (KEK)
• 74
With the ever increasing amount of precise data available for hadron production processes, the perturbative QCD framework is being extended to explore effects and corrections that go beyond the next-to-leading order (NLO) accuracy. Fixed order calculations at next-to-next-to-leading order (NNLO) are becoming the new necessary standard required for precision predictions and, consequently, the analysis of the non-perturbative structure of the hadron has to align to this standard. Moreover, relevant effects specific to some kinematical regions, such as the small-x and large-x regions in Semi-Inclusive electron-positron Annihilation (SIA), can be investigated through the means of resummation techniques and can be also included in the analysis of final state parton distribution functions. In this talk we present a first analysis of parton-to-pion fragmentation functions at next-to-next-to-leading order based on single-inclusive pion production in electron-positron annihilation, together with its extension to the small-x region where an all order resummation of large logarithmic contributions has to be included to further extend the lower cuts on the fit's domain.
Speaker: Mr Daniele Paolo Anderle (Institut für Theoretische Physik Universität Tübingen)
• WG1/WG7 joint session (PDF+future exp.) Auditorium

### Auditorium

#### DESY Hamburg

Notkestr. 85 D-22607 Hamburg Germany
Conveners: Claire Gwenlan (Oxford), Dr Elke-Caroline Aschenauer (BNL), Dr Katarzyna Wichmann (DESY), Prof. Robert Thorne (University College London), Prof. Ronan McNulty (University College Dublin), Dr Wally Melnitchouk (Jefferson Lab)
• 75
Measurement of forward direct photon production in p–A at LHC with ALICE – a probe for nuclear PDFs and saturation
Direct photon production at forward rapidity is a promising probe for the gluon content of protons and nuclei at small x. In particular, the measurement of the nuclear modification factor for direct photons in p–A collisions at the LHC should provide a crucial test for gluon saturation. We discuss the unique role of such a photon measurement in the context of other measurements at the LHC and also of possible future measurements at EIC. To allow us to perform this measurement, a new forward calorimeter (FoCal) is proposed as an upgrade to the ALICE experiment. The proposed detector covers the range 3.5 < eta < 5 which probes the gluon distributions at x ~ 10^-5 and Q ~ pT > 4 GeV. We will discuss performance studies of such a detector, which demonstrate that extremely high-granularity calorimetry is required for a successful measurement, and show a few recent results from R&D for this project.
Speaker: Prof. Thomas Peitzmann (Utrecht University)
• 76
PDF and $alpha_s$ determination at the LHeC and FCC-he
An update is presented on the possibilities for precision QCD studies at the LHeC and the FCC-he. Specifically, we will show recent results on the determination of nucleon PDFs with complete flavour decomposition and of the value of the strong coupling constant with per mille accuracy. The implications of such measurements on Higgs physics and on high mass BSM searches at the HL-LHC will be discussed.
Speaker: Prof. Amanda Cooper-Sarkar (Oxford University)
• 77
Parton distributions at a 100 TeV hadron collider
We discuss the role of QCD and precision SM calculations for the physics program of a 100 TeV hadron collider. In particular, we discuss the role of parton distributions, jet and top quark production, electroweak and photon-induced corrections and global event properties at 100 TeV. This talk summarizes the Standard Model chapter of the FCC-hh Conceptual Design Report.
Speaker: Juan Rojo (Oxford)
• 78
eA physics at the LHeC
In this talk we will present a review on the possibilities for nuclear studies at the LHeC and the FCC-he. We will show an update on the possibilities for a precise determination of nuclear PDFs, and their complete unfolding, in a kinematic region never explored before in DIS. We will also discuss diffractive and exclusive observables and the possibilities which these offer for constraining nuclear GPDs and for disentangling the relevance of non-linear dynamics in nuclei. Finally, we will show prospects for jet physics and for studies of QCD radiation in the nuclear medium, of relevance for ultra-relativistic heavy-ion collisions.
Speaker: Dr Ilkka Helenius (Lund University)
• WG3 Electroweak Physics and Beyond the Standard Model SR2

### SR2

#### DESY Hamburg

Conveners: Prof. Kevin Black (Boston University), Prof. Sanjay Padhi (Brown University), Prof. Shufang Su (University of Arizona)
• 79
Search for low mass Higgs-boson like resonances at CMS
A search is performed on the 8 TeV LHC data for additional scalars and pseudoscalar with masses below the newly discovered higgs boson h(125). These searches are motivated within several BSM theories, most significantly extensions of the non mininal extensions of the MSSM like the NMSSM, where additional scalar and pseudoscalar states are expected. The mass range from 350 MeV to 110 GeV is explored with different final states. The current status of these searches will be reviewed and prospects will be given to extend these searches in the Run2 of the LHC.
Speaker: Benoit Courbon (Institut de Physique Nucléaire, IN2P3-CNRS)
• 80
Search for heavy Higgses and di-Higgs resonances in fermionic decay modes, by the ATLAS collaboration.
Several "Beyond Standard Model" theories predict the existence of additional heavy Higgs particles or di-Higgs resonances, with sizeable contributions of fermionic decay channels. Searches are presented using the first run-2 data of 3.2 fb^(-1) at 13 TeV.
Speaker: Dirk Duschinger (TU Dresden)
• 81
Search for additional heavy scalar/pseudoscalar neutral Higgs bosons at CMS
Recent results on searches for additional scalar and pseudo-scalar neutral Higgs bosons are presented. These searches are well motivated within a variety of BSM models, from the MSSM or NMSSM to more general two Higgs doublet models. Heavy neutral scalar higgs (H) or pseudo-scalar (A) are searched in different final states. These studies are based on pp collision data collected at centre-­of-­mass energies of 7 and 8 TeV by the CMS collaboration at the LHC.
Speaker: Ram Krishna Dewanjee (Tata Institute of Fundamental Research in Mumbai, India)
• 82
Searches for diboson resonances with the ATLAS detector at the LHC
Resonant production of two bosons (gammagamma, VV, VH and HH) is a clear hint for physics beyond the Standard Model, potentially related to the nature of electroweak symmetry breaking mechanism in the SM. Searches for diboson resonances have been performed in gammagamma and in final states with different numbers of leptons and jets including cases where the two jets are merged into one because of the large boost. ATLAS searches for diboson resonances with LHC Run 2 data at 13 TeV are summarized in this talk.
Speaker: Daniel Buescher (Uni Freiburg)
• WG4 Heavy Flavours SR3 (DESY, Hamburg)

### SR3

#### DESY, Hamburg

Conveners: Mr Martijn Mulders (CERN), Maximilian Stahlhofen (DESY), Mr Mikhaylo Lisovyi (DESY/Hamburg Uni)
• 83
13 TeV cross-section measurements at LHCb
By using the very first proton-proton collision data of the LHC Run II, LHCb performed a series of measurements, notably including the cross-sections for heavy boson, quarkonia, beauty and charm productions. The results have been carried out by exploiting a new scheme for the LHCb software trigger that gives the possibility to finalise physics analyses directly from data objects produced by the online reconstruction. Physics results will be discussed with some emphasis on the performance and technical implementation of this novel trigger approach.
Speaker: Tomasz Szumiak (Cracow-AGH)
• 84
Heavy Flavour results from CMS
The available statistics of heavy flavored particles collected at the LHC in pp collisions at 7, 8 and 13 TeV provides an excellent opportunity to test the standard model and probe for new physics effects. A review of selected recent measurements on heavy flavors (production and propeties, rare decays, CP violation, exotic and standard quarkonia) by CMS based on LHC Run I and Run II data is presented.
Speaker: Prof. Kai-Feng Chen (National Taiwan University)
• 85
Recent results on B-Physics and Quarkonia with the ATLAS detector
This talk will report on four measurement recently completed by ATLAS: (a) the decay of Lambda_b into Lambda and psi(2S), observed for the first time and compared to the decay into Lambda and J/psi; (b) the decay of Bc into J/psi Ds and J/psi Ds*, including the first polarisation measurement for the latter channel; (c) the measurement of the ratio of the fragmentation fraction f_s/f_d, which complements a previous measurement of LHCb over a different range of pT and y; (d) B+ mass reconstruction in the decay of B+ to J/psi and K+ at ATLAS at 13 TeV pp collisions; (e) Measurement of the differential non-prompt Jpsi production fraction at 13 TeV
Speaker: Artem Maevskiy (M.V. Lomonosov Moscow State University)
• 86
Charm hadroproduction in the atmosphere, QCD and neutrino astronomy
We update predictions for lepton fluxes from the hadroproduction of charm quarks in the scattering of primary cosmic rays with the Earth's atmosphere. The calculation of charm-pair hadroproduction applies the latest results from perturbative QCD through next-to-next-to-leading order and modern parton distributions, together with estimates on various sources of uncertainties. Our predictions for the lepton fluxes turn out to be compatible, within the uncertainty band, with recent results in the literature. However, by taking into account contributions neglected in previous works, our total uncertainties are much larger. The predictions are crucial for the interpretation of results from neutrino experiments like IceCube, when disentangling signals of neutrinos of astrophysical origin from the atmospheric background.
Speaker: Sven-Olaf Moch (UHH)
• WG5 Small-x and Diffraction SR4b

### SR4b

#### DESY Hamburg

Conveners: Dr Alessia Bruni (INFN Bologna), Leszek Motyka (Jagiellonian University), Dr Rainer Schicker (Phys. Inst., Heidelberg)
• 87
BFKL effects and central rapidity dependence in Mueller-Navelet jet production at 13 TeV LHC
In this talk a study of the production of Mueller-Navelet jets at 13 TeV LHC will be presented, including the BFKL resummation effects and investigating three different variants of the BLM scale optimization method. It will be shown how the cross section and the azimuthal observables are affected by the exclusion of the events where, for a given rapidity interval between the two jets, one of these is produced in the central region.
Speaker: Mr Francesco Giovanni Celiberto (Università della Calabria and INFN-Cosenza (Italy))
• 88
Inclusive four-jet production: a study of Multi-Regge kinematics and BFKL observables
In this talk a study of differential cross sections for the production of four jets in multi-Regge kinematics will be presented, the main focus lying on azimuthal angle dependences. The theoretical setup consists in the jet production from a single BFKL ladder with a convolution of three BFKL Green functions, where two forward/backward jets are always tagged in the final state. Furthermore, the tagging of two further jets in more central regions of the detectors with a relative separation in rapidity from each other is requested. It is found, as result, that the dependence on the transverse momenta and the rapidities of the two central jets can be considered as a distinct signal of the onset of BFKL dynamics.
Speaker: Mr Francesco Giovanni Celiberto (U. Calabria & INFN-CS (Italy); IFT UAM/CSIC Madrid)
• 89
Inclusive three jet production at the LHC for 7 and 13 TeV collision energies
First, we define new observables sensitive to BFKL dynamics in the context of multijet production at the Large Hadron Collider. We propose the study of the inclusive production of three jets well separated in rapidity from each other, with two of them being very forward. We show that the tagging of a third jet in the central region of rapidity allows for a very strong test of the BFKL formalism. We study two projections on azimuthal angles for the differential cross section which allow for the definition of many different observables whose behavior when varying the pt and rapidity of the central jet is a distinct signal of BFKL dynamics. Then, we present a first full phenomenological study of ratios of correlation functions of products of cosines of azimuthal angle differences among the tagged jets.
Speaker: Dr Grigorios Chachamis (IFT UAM-CSIC)
• 90
The high-energy radiation pattern from BFKLex
We will present a study of high-energy jet production in the multi-Regge limit making use of the Monte Carlo code BFKLex which includes collinear improvements in the form of double-log contributions. Making use of the anti-kt jet algorithm in the FastJet implementation, we will present results for the average transverse momentum and azimuthal angle of the produced jets when two tagged forward/backward jets are present in the final state. We also introduce a new observable which accounts for the average rapidity separation among subsequent emissions.
Speaker: Dr Grigorios Chachamis (IFT UAM-CSIC)
• WG6 Spin Physics SR4a

### SR4a

#### DESY Hamburg

Conveners: Dr Emanuele Roberto Nocera (Rudolf Peierls Centre for Theoretical Physics University of Oxford), Dr Erin Seder (CEA Saclay DSM/IRFU/SPhN/LSN), Dr Salvatore Fazio (Brookhaven National Laboratory), Dr Silvia Pisano (Laboratori Nazionali di Frascati - INFN)
• 91
Recent COMPASS results on Transverse Spin and Momentum dependent distributions and fragmentation functions.
COMPASS is a fixed target experiment in operation at CERN since 2002 with a wide physics programme. By using either muon or hadron beams, both the study of the spin structure of the nucleon and the search of exotic states in hadron spectroscopy are performed. An important part of this programme is the study of transverse spin and momentum dependent parton distribution and fragmentation functions. First measurements of HERMES and COMPASS showed sizeable Collins and Sivers asymmetries, allowing first extractions of TMD PDFs and FF. Now this field of research is entering the phase of precision measurements and is a central topic of many present and future experiments. Recent COMPASS results on Collins and Sivers asymmetries and on multidimensional analysis of SSA will be reviewed together with the perspective for future measurements.
Speaker: Dr Andrea Bressan (University of Trieste and Trieste Division of INFN)
• 92
Polarised Drell-Yan Process in the COMPASS Experiment
The COMPASS experiment at CERN has been contributing to the knowledge on the nucleon structure, and its description in terms of the Transverse Momentum Dependent Parton Distribution Functions (TMD PDFs), accessed through the SIDIS process. In 2014/2015 the data taking was dedicated to the polarised Drell-Yan (DY) measurement with a negative pion beam and a transversely polarised proton target, as well as unpolarised nuclear targets. These data are now being analysed. The predicted sign change in the Sivers distribution when accessed from DY with respect to SIDIS will be measured. The details on the experimental setup, the covered phase space, a preliminary first look into data distributions and predictions for the full data sample will be presented.
Speaker: Márcia Quaresma (LIP - Lisbon)
• 93
The gluon Sivers asymmetry measurements at COMPASS
The Sivers effect describes the correlation between the spin of the nucleon and the orbital motion of partons. For gluons it has been measured at COMPASS via $J/\Psi$ production and via high-$p_T$ hadron pair production in Semi-Inclusive Deep Inelastic Scattering of a 160 GeV/$c$ muon beam off transversely polarised proton and deuteron targets by determining the amplitude of the modulation of the Sivers angle $\phi^{Siv}$ distribution. Both the approach using $J/\Psi$ channel and high-$p_T$ hadron pair selection will be described in detail and the results given.
Speaker: Mr Adam Szabelski (University of Trieste)
• 4:00 PM
Coffee break
• WG1/WG2 joint session (QCD and PDF) Auditorium

### Auditorium

#### DESY Hamburg

Conveners: Frank Tackmann (DESY), Dr Katarzyna Wichmann (DESY), Prof. Robert Thorne (University College London), Prof. Ronan McNulty (University College Dublin), Dr Shima Shimizu (Kobe University), Dr Simon Plätzer (DESY Theory Group)
• 94
Jet Production at Low Momentum Transfer at HERA
The production of inclusive jets as well as of dijet and trijet topologies is investigated at HERA in the domain of low momentum transfer Q2 < 100 GeV2, using the H1 experiment. The new data complement a previous measurement done at higher momentum transfer. The value of the strong coupling constant α_s(M_Z) is extracted and its running is probed.
Speaker: Daniel Britzger (DESY)
• 95
Jet measurements at 2.76, 7 and 8 TeV from CMS
We present recent jets results from CMS at at 2.76, 7 and 8 TeV and show comparison to theory calculations. Inclusive jet cross sections as well as azimuthal correlations between jets are presented.
Speaker: Mr Paolo Gunnellini (Deutsches Elektronen Synchrotron (DESY))
• 96
PDF constraints and a_s results from CMS
We present and discuss the impact of the most recent CMS data on the precision measurement of a_s and parton density functions.
Speaker: Mr Engin Eren (DESY)
• WG3 Electroweak Physics and Beyond the Standard Model SR2

### SR2

#### DESY Hamburg

Conveners: Prof. Kevin Black (Boston University), Prof. Sanjay Padhi (Brown University), Prof. Shufang Su (University of Arizona)
• 97
Measurement of WW and WZ production cross section at 8TeV and 13 TeV and limits on anomalous triple gauge couplings with the ATLAS detector (WG3)
Measurements of the cross sections of the production of pairs of electroweak gauge bosons at the LHC constitute stringent tests of the electroweak sector of the Standard Model and provide a model-independent means to search for new physics at the TeV scale. The ATLAS collaboration has performed measurements of integrated and differential cross sections of the production of WW and WZ pairs in both fully leptonic and semi-leptonic final states, both at 8 TeV and 13 TeV collision energy. These measurements are compared to predictions at up to NNLO+NNLL in pQCD. First integrated measurements of the WW and WZ pair production cross sections using fully leptonic final states at 13 TeV using data corresponding to 3.2 /fb are presented. Detailed studies of integrated and differential cross sections have been performed using data corresponding to 20.3 /fb at a centre-of-mass energy of 8 TeV. The measurements are performed as a function of hadronic jet multiplicity, a variety of kinematic variables calculated from the leptons and for the case of the WZ events also for the ratio of W+Z over W-Z events. Semi-leptonic final states are used to complement studies at higher transverse momentum of the vector bosons. Constraints on new physics are provided by setting limits on anomalous triple gauge couplings for charged vector bosons.
Speaker: Mr Felix Socher (Institut für Kern- und Teilchenphysik, Dresden)
• 98
Measurement of the ZZ(*) and Zgamma production cross sections at 8 TeV and 13 TeV and limits on anomalous triple gauge couplings with the ATLAS detector (WG3)
Measurements of the cross sections of the production of pairs of electroweak gauge bosons at the LHC constitute stringent tests of the electroweak sector of the Standard Model and provide a model-independent means to search for new physics at the TeV scale. The ATLAS collaboration has measured inclusive and differential cross sections of the production of ZZ pairs and Z and photon pairs, using final states with the Z decaying to charged leptons or neutrinos. First integrated measurements of the ZZ pair production cross sections using fully leptonic final states at 13 TeV using data corresponding to 3.2 /fb are presented. Detailed studies of integrated and differential cross sections have been performed using data corresponding to 20.3 /fb at a centre-of-mass energy of 8 TeV. The measurements are performed as a function of a variety of kinematic variables calculated from the leptons, like the transverse momentum or rapidity of the vector bosons. For the case of the production of four charged leptons a measurement of the four-lepton invariant mass spectrum ranging from 80 to 1000 GeV was performed, where several distinct physics processes give rise to the production of 4-lepton final state. All measurements are compared to calculations at up to NNLO in pQCD. Constraints on new physics are provided by setting limits on anomalous triple couplings between neutral vector bosons, which are forbidden at tree level in the Standard Model.
Speaker: Stamatios Gkaitatzis (Aristotle Univ. of Thessaloniki)
• 99
Electroweak production of single vector bosons, vector boson scattering, and triple gauge-boson production with the ATLAS detector (WG3)
The production of single W and Z bosons with two jets at high invariant mass has been studied by the ATLAS collaboration in detail using data corresponding to 20.3 /fb at a centre-of-mass energy of 8 TeV. Integrated and differential cross sections are measured in many different phase space regions with varying degree of sensitivity to the electroweak production in vector boson fusion. The cross section for the electroweak production has been extracted for both integrated and for the first time differential distributions. The results have also been used to derive limits on anomalous triple gauge couplings. Vector-boson scattering processes provide a unique way to probe the mechanism of electroweak symmetry breaking. Similar physics can be probed by studying the production of three gauge bosons. The results can also be used for a model-independent search for new physics at the TeV scale via anomalous quartic gauge couplings. The ATLAS collaboration has studied vector boson scattering in final states with two gauge bosons and two forward jets in 20.3 /fb of 8TeV proton-proton collision data, in particular two same-sign W bosons, a WZ boson pair, and a W or Z boson in association with an isolated photon. The studies are complemented by a search for anomalous vector boson production of WW+WZ pairs in their semileptonic decays to lnujj in association with two forward jets. A measurement of exclusive production of W boson pairs produced by the interaction of two photons will be presented. This topology is found to provide strong constraints on anomalous quartic gauge couplings. The collaboration has used this data set as well to study the production of three gauge bosons. A search was carried out for the production of three W bosons. The cross sections for the production of a W or Z boson in association with two isolated photons has been measured. For the Z boson, decays into charged leptons as well as neutrinos have been studied.
Speaker: Mr Christian Gumpert (TU Dresden)
• 100
Multiboson measurements from CMS (Run I)
Overview of the latest legacy measurements of multibosons with CMS
Speaker: Jing Li (Peking University in Beijing, China)
• 101
Multiboson measurements from CMS (Run II)
Early results from Run II multiboson measurements with CMS
Speaker: Xavier Coubez (Institut Pluridisciplinaire Hubert Curien, IN2P3-CNRS - ULP, UHA Mulhouse in Strasbourg, France)
• WG4 Heavy Flavours SR3

### SR3

#### DESY Hamburg

Conveners: Mr Martijn Mulders (CERN), Maximilian Stahlhofen (DESY), Mr Mikhaylo Lisovyi (DESY/Hamburg Uni)
• 102
Combined analysis of charm-quark fragmentation-fraction measurements
A summary of measurements of the fragmentation of charm quarks into a specific hadron is given. Measurements performed in photoproduction and deep inelastic scattering in e+-p, pp and e+e- collisions are compared, using up-to-date branching ratios. Within uncertainties, all measurements agree, supporting the hypothesis that fragmentation is independent of the specific production process. Compared to individual measurements, the averaged fragmentation fractions have significantly reduced uncertainties. Implications of results for other physical quantities are considered.
Speaker: Dr Oleksandr Zenaiev (DESY)
• 103
Progress in the calculation of 3-loop corrections to the heavy flavor Wilson coefficients in DIS
We report on the current status of the ongoing calculation of 3-loop heavy flavor corrections to deep inelastic structure functions at large virtualities.
Speaker: Abilio De Freitas (DESY - Zeuthen)
• 104
A determination of mc(mc) from HERA data using a matched heavy quark scheme
In this talk I will present a novel determination of the mass of the charm quark extracted by analyzing the statistical quality of fits of parton distribution functions (PDFs) to inclusive and exclusive charm deep-inelastic scattering (DIS) cross-section data from Runs I and II of the HERA collider. We employ the running mass definition in the MSbar scheme, which improves the perturbative stability as compared to the pole-mass definition, in the framework of the FONLL general-mass scheme. The analysis is based on the xFfitter framework, with structure functions computed in the FONLL scheme as implemented in the APFEL code.
Speaker: Dr Valerio Bertone (University of Oxford)
• 105
Impact of heavy flavor (extrinsic & intrinsic) for LHC processes
As the energy of the LHC increases, the heavy quarks play a more significant role. We examine both the impact of the heavy quarks on the predictions for processes such as boson production (both with and without an associated heavy quark), and consider methods to constrain the heavy quark PDFs.
Speaker: Prof. Fred Olness (SMU)
• 106
Bottom-quark mass effects in bbH production.
After carefully explaining how fixed and variable flavour schemes arise in the context of DIS, I will discuss how one can consistently combine the merits of the two. The final matched result includes the full power corrections of the fixed-flavour scheme and resums the potentially large logs. I will then talk about the application of this approach to the case of bbH at the LHC and present a fair and thorough comparison to the other existing predictions in the literature.
Speaker: Andrew Papanastasiou (Cavendish Laboratory, University of Cambridge)
• 107
Probing nuclear gluons with heavy flavors at an Electron-Ion Collider
We study the prospects for measuring nuclear modifications of the gluon density (gluonic EMC effect, antishadowing, shadowing) using open heavy flavor production (charm, beauty) at a future Electron-Ion Collider (EIC). Such direct measurements complement indirect studies of nuclear gluons through DGLAP evolution and could substantially advance our understanding of QCD in nuclei. Building on the experience with HERA, we discuss (a) the expected heavy quark production rates on nuclei at EIC; (b) the possible methods of charm/beauty reconstruction at EIC and their requirements; (c) prospects of open charm/beauty measurements at x > 0.1; (d) specifics of nuclear ratio measurements of heavy meson production. We report about results from an on-going R&D project dedicated to heavy flavor production at EIC (process simulations, physics impact).
Speaker: Christian Weiss (Jefferson Lab)
• WG5 Small-x and Diffraction SR4b

### SR4b

#### DESY Hamburg

Conveners: Dr Alessia Bruni (INFN Bologna), Leszek Motyka (Jagiellonian University), Dr Rainer Schicker (Phys. Inst., Heidelberg)
• 108
Exclusive production observed at the CMS experiment
Exclusive W+ W- pair production in photon-photon collisions during the pp runs at 7 and 8TeV are observed and used to put constraints on the Anomalous Quartic Gauge Couplings. During the proton lead collisions in photon-induced vector meson production is observed via the decay of Ypsilon into two muons. The slope of the squared pT distribution is measured to determine the size of the production region.
Speaker: Ruchi Chudasama (Bhabha Atomic Research Centre in Mumbai, India)
• 109
Central Exclusive production at LHCb
The cross-section for central exclusive production of J/psi and Psi(2S) mesons at 13 TeV is measured using the LHCb detector. Proton dissociative backgrounds are significant reduced compared to previous measurements through the use of forward shower counters, recently installed for Run 2. Cross-section ratios to previous measurements at 7 TeV allow more precise tests of theoretical predictions and constraints on the parton distribution functions
Speaker: Prof. Ronan McNulty (University College Dublin)
• 110
Exclusive pi+ pi- production at 7TeV
We report a measurement of exclusive pion pair production in proton-proton collisions, dominated by $p + p \rightarrow p^{(*)} + \pi^{+} \pi^{-} + p^{(*)}$, where the $\pi^{+} \pi^{-}$ pair is produced at central rapidities $y$ and the incident protons stay intact or dissociate without being detected. The measurement is performed with the CMS detector at the LHC, using an integrated luminosity of 450~$\mu b^{-1}$ collected at a center-of-mass energy of $\sqrt{s}$ = 7 \TeV in 2010. The cross section measured in the phase space defined by $p_{T}(\pi)>0.2$~GeV/c and $|y(\pi)|< 2$ is $20.5~\pm{0.3~(stat)}~\pm {3.1~(syst)}~\pm~{0.8~(lumi)}~\mu b$. The differential $\pi^{+}\pi^{-}$ cross sections as a function of invariant mass, $p_{T}$, and $y$, and the single $\pi$ cross section as a function of $p_{T}$, are also shown and compared to model predictions.
Speaker: Mohsen Khakzad (Institute for Studies in Theoretical Physics & Mathematics (IPM) in Tehran, Iran)
• 111
Exclusive diffractive production of $\pi^+ \pi^-$ pairs within tensor pomeron approach
We discuss exclusive central diffractive dipion production in the reactions $pp \to pp \pi^{+} \pi^{-}$ and $p\bar{p} \to p\bar{p} \pi^{+} \pi^{-}$ at high energies. The calculation is based on a tensor pomeron model and the amplitudes for the processes are formulated in an effective field-theoretic approach [1]. We include the purely diffractive dipion continuum, and the scalar and tensor resonances decaying into the $\pi^{+} \pi^{-}$ pairs [2, 3] as well as the photoproduction contribution ($\rho^{0}$, Drell-S\"oding) [4]. We discuss how two pomerons couple to tensor meson $f_{2}(1270)$ and the interference effects of resonance and dipion continuum for the first time. The theoretical results are compared with existing STAR, CDF, and CMS experimental data. Predictions for planned or being carried out experiments (ALICE, ATLAS) are presented. We show the influence of the experimental cuts on the integrated cross section and on various differential distributions for outgoing particles. Distributions in rapidities and transverse momenta of outgoing protons and pions as well as correlations in azimuthal angle between them are presented. We find that the relative contribution of resonant $f_2(1270)$ and dipion continuum strongly depends on the cut on proton transverse momenta (or four-momentum transfer squared $t_{1,2}$) which may explain some controversial observations made by different ISR experiments in the past. The cuts may play then the role of a $\pi \pi$ resonance filter. We suggest some experimental analyses to fix model parameters related to the pomeron-pomeron-meson coupling. References 1. C. Ewerz, M. Maniatis, and O. Nachtmann, Annals Phys. 342 (2014) 31 2. P. Lebiedowicz, O. Nachtmann, and A. Szczurek, Annals Phys. 344 (2014) 301 3. P. Lebiedowicz, O. Nachtmann, and A. Szczurek, arXiv:hep-ph/1601.04537 4. P. Lebiedowicz, O. Nachtmann, and A. Szczurek, Phys. Rev. D91 (2015) 074023
Speaker: Dr Piotr Lebiedowicz (Institute of Nuclear Physics, Polish Academy of Sciences)
• 112
Resonance production in Pomeron-Pomeron collisions at the LHC
A Regge pole model for Pomeron-Pomeron total cross section in the resonance region $\sqrt{M^2}\le$ 5 GeV is presented. The cross section is saturated by direct-channel contributions from the Pomeron as well as from two different $f$ trajectories, accompanied by the isolated f$_0(500)$ resonance dominating the $\sqrt{M^{2}}\leq 1$ GeV region. A slowly varying background is taken into account. The calculated Pomeron-Pomeron total cross section cannot be measured directly, but is an essential part of central diffractive processes. In preparation of future calculations of central resonance production at the hadron level, and corresponding measurements at the LHC, we normalize the Pomeron-Pomeron cross section at large masses $\sigma_{t}^{PP} (\sqrt{M^2}\rightarrow \infty) \approx$ 1 mb as suggested by QCD-motivated estimates.
Speaker: Dr Rainer Schicker (Phys. Inst., Heidelberg)
• WG6 Spin Physics SR4a

### SR4a

#### DESY Hamburg

Conveners: Dr Emanuele Roberto Nocera (Rudolf Peierls Centre for Theoretical Physics University of Oxford), Dr Erin Seder (CEA Saclay DSM/IRFU/SPhN/LSN), Dr Salvatore Fazio (Brookhaven National Laboratory), Dr Silvia Pisano (Laboratori Nazionali di Frascati - INFN)
• 113
Lorentz invariance relations for twist-3 functions and frame-independence of twist-3 cross sections
We derive a complete set of relations among twist-3 distribution and fragmentation functions based on the QCD equation-of-motion and identities among nonlocal operators which fully incorporate the constraints from Lorentz invariance. We show that the dynamical twist-3 functions constitute a complete set of twist-3 functions and other types of twist-3 functions can be expressed in terms of the dynamical ones and the twist-2 functions. We also show that those relations guarantee the frame-independence of the twist-3 observables.
Speaker: Prof. Yuji Koike (Department of Physics, Niigata University)
• 114
Twist-3 effects on the double spin asymmetry A_{LT} in proton-proton collision.
We discuss the twist-3 contributions to the double-spin asymmetry A_{LT} for light hadron production in collisions between transversely and longitudinally polarized protons. So far only twist-3 effect in the transversely polarized proton have been studied for A_{LT}. In this talk, we discuss other possible twist-3 contributions in order to derive the complete leading-order cross section formula for A_{LT}.
Speaker: Dr Shinsuke Yoshida (Central China Normal University)
• 115
Twist-3 approach to hyperon polarization in unpolarized proton-proton collision
We study the transverse porlarization of hyperons produced in the high-energy unporlarized proton-proton collision in the framework of the collinear factorization. This phenomenon is one of the twist-3 observables and twist-3 distribution and fragmentation functions contribute. In this work, we focus on the former contribution and derive the LO complete cross-section. For the soft-gluon-pole term, we develope the”Master formula” which simplify the procedure of calculation and show explicitly that only the derivative term contributes. Moreover, we calculate the soft-felmion-pole contribution for the first time and show that it vanishes. These results provide a useful tool to explain the mechanism of the hyperon porlarization.
Speaker: Mr Kenta Yabe (Niigata University)
• 116
Charged pion, kaon, and unidentified hadron multiplicities in semi-inclusive deep-inelastic scattering (SIDIS) from COMPASS
The latest measurements of charged pion, kaon, and unidentified hadron multiplicities in semi-inclusive deep-inelastic scattering from the COMPASS experiment at CERN are presented. The data were collected using a 160 GeV muon beam incident on an isoscalar 6LiD target. The large statistics collected cover a wide kinematic range in photon virtuality: 1 < Q2 < 50 (GeV/c)2, relative virtual-photon energy: 0.1 < y < 0.7 , Bjorken scaling variable: 0.004 < x < 0.4, and relative hadron energy: 0.2 < z < 0.85. In addition, we present the charge sum of the multiplicities integrated over z. The results of the pion and unidentified hadron sums are in very good agreement with LO expectations, while the results of the kaon sum show a different x dependence than that predicted using the current DSS ratio of fragmentation functions Dstr/Dfav.
Speaker: Dr Erin Seder (CEA Saclay DSM/IRFU/SPhN/LSN)
• 117
Inclusive cross sections for pairs of identified light charged hadrons and single protons from Belle e+e− annihilation data
Inclusive cross sections and azimuthal asymmetries were extracted from e+e− annihilation data collected with the Belle detector. These data were taken at the KEKB e+e− collider at a center-of-mass energy of around sqrt(s) = 10.58 GeV. The cross sections for single-hadron and hadron-pair production provide very clean information on the spin-independent fragmentation functions, which describe the spin-independent hadronization of quarks into final-state hadrons. The cross-section measurement for single protons extend the earlier measurements of single-pion and single-kaon production, providing new constraints on the fragmentation functions. Measurements of single-hadron cross sections, however, do not distinguish between favored and disfavored fragmentation. Measurements of hadron pairs, where the hadrons are nearly back to back, do provide sensitivity to favored and disfavored fragmentation, thereby providing additional invaluable input for the analysis of the nucleon structure studied in semi-inclusive deep-inelastic scattering and proton-proton collisions The recent status of the Belle measurement for single-proton cross sections and cross sections for various combinations of pairs of pions and kaons as well as of azimuthal asymmetries will be presented.
Speaker: Ms Charlotte Van Hulse (University of the Basque Country)
• 118
Collins function from recent e+e− data
New investigations on the Collins functions have been made possible by recent e+ e− annihilation data released by the BaBar Collaboration. These data allow to directly infer the transverse momentum dependence of the Collins function for pions and, for the first time, attempt extractions of the kaon Collins function. In this talk, I will discuss our recent results of the analysis of these and other available data sets, within a simple gaussian model.
Speaker: Dr J. Osvaldo Gonzalez Hernandez (Old Dominion University)
• WG7 Future Experiments SR1

### SR1

#### DESY Hamburg

Conveners: Claire Gwenlan (Oxford), Dr Elke-Caroline Aschenauer (BNL), Dr Wally Melnitchouk (Jefferson Lab)
• 119
The International Linear Collider - Physics & Perspectives
With the discovery of the Higgs boson at LHC, all particles of the Standard Model have been observed experimentally, yet many questions are left unanswered. The discovery has intensified the planning for future high-energy colliders, which aim to probe the Standard Model and the mechanism of electroweak symmetry breaking with higher precision and to extend and complement the search for new particles currently under way at the LHC. The most mature option for such a future facility is the International Linear Collider ILC, an electron-positron collider with a center-of-mass energy of 500 GeV, and the potential for upgrades into the TeV region and/or into a photon collider. The ILC will fully explore the Higgs sector, including model-independent coupling and width measurements, direct measurements of the coupling to the top quark and the Higgs self-coupling, enable precision measurements of top quark properties and couplings as well as other electroweak precision measurements and provide extensive discovery potential for new physics complementary to the capabilities of hadron colliders. We will give an overview over the physics case of the ILC, put in context of the running scenario covering different center-of-mass energies, and discuss the current status and perspectives of this global facility.
Speaker: Naomi van der Kolk (MPI Muenchen)
• 120
The LHeC project and detector
The Large Hadron Electron Collider is the proposal of an upgrade of the LHC to study ep/eA collisions with a centre-of-mass energy in the TeV regime using an about 60 GeV electron beam. In the future, the lepton beams could be combined with the HE-LHC or FCC hadron beams, to study DIS at even higher energies. In this talk we will present an update of the status of the project, with emphasis on the accelerator development, the design of a demonstrator for the high-current multi-pass energy recovery concept and an overview on further developments towards an update of the 2012 LHeC Conceptual Design Report in the coming years.
Speaker: Paul Newman
• 121
Higgs physics at the LHeC and FCC-he
In this talk, we review the possibilities for Higgs studies at the LHeC and the FCC-he. Specifically, we will show recent results on the determination of the $H\to b \bar b$ coupling, and on the progress in the $H\to c \bar c$. We will then discuss the possibility to study at LHeC the coupling of Higgs to the 'dark sector. The final topic is HH production at FCC-he and the sensitivity to anomalous (=BSM) couplings.
Speaker: Olaf Behnke (DESY)
• 122
Physics case of the very high energy electron-proton collider
The possibility of using plasma wakefield acceleration to build an electron-proton collider (VHEeP) at a centre-of-mass energy of 9 TeV was presented at the DIS2015 workshop. In this talk, the physics case is further developed, with more detailed studies at low parton momentum fractions, x, down to 10^-8. The VHEeP collider also has sensitivity to the production of leptoquarks approaching the kinematic limit and thus extends the reach currently accessible. Other exotic physics such as a quark sensitivity can also be probed at higher energies or smaller distances. These and other studies are presented, demonstrating that an ep collider with an energy a factor of 30 above HERA has sensitivity to new physical phenomena.
Speaker: Matthew Wing (UCL)
• 123
Small-x physics at the LHeC
In this talk we will present a review on the possibilities for small-x studies at the LHeC and the FCC-he. We focus on the possibilities of discriminating standard DGLAP approaches from resummation and saturation scenarios in inclusive, semi-inclusive and exclusive observables. We also discuss the opportunities for studying a totally new kinematic regime in diffractive production, and for analysing the 3D proton structure through different observables constraining GPDs.
Speaker: Claire Gwenlan (Oxford)
• 6:40 PM
Bus transfer to concert hall - Buses leave DESY between 18:40 and 18:50
• 7:30 PM
Public Lecture Laeiszhalle (Hamburg)

### Laeiszhalle

#### Hamburg

• 8:15 PM
Concert Laeiszhalle

### Laeiszhalle

#### DESY Hamburg

• 9:15 PM
Bus transfer to DESY, stop at Altona and Bahrenfelder Trabrennbahn
• Wednesday, April 13
• WG2/WG3 joint session (QCD+EW) SR1

### SR1

#### DESY Hamburg

Conveners: Frank Tackmann (DESY), Prof. Kevin Black (Boston University), Prof. Sanjay Padhi (Brown University), Dr Shima Shimizu (Kobe University), Prof. Shufang Su (University of Arizona), Dr Simon Plätzer (DESY Theory Group)
• 124
Precision studies of Drell-Yan transverse momentum distributions and the polarisation angular coefficients in Z boson decays with the ATLAS detector (WG2)
The ATLAS collaboration has performed precision measurements sensitive to the transverse momentum of the Z/gamma* bosons, both directly through the transverse momentum of the di-lepton pair and through the angular decorrelation as measured in the phi* observable. These measurements are sensitive to soft resummation effects and hard jet emissions for small and large momentum transfers, respectively, probing QCD in a unique way. The studies carried out with 20.3 /fb of data at a center-of-mass energy of 8TeV probe a wide di-lepton invariant mass region from 12 GeV to 150 GeV, both integrated and differential in the di-lepton rapidity. The measurements are compared to a variety of resummation calculations and parton shower Monte Carlos at up to NNLO+NNLL as well as fixed order predictions at NNLO QCD including NLO electroweak corrections. The precision measurement of angular distributions of the Drell-Yan lepton pairs around the Z-boson mass peak provide a stringent test of the underlying QCD dynamic of the Z-boson production mechanisms through spin-correlation effects between initial and final state. A measurement is presented of the complete set of eight angular coefficients describing these distributions as determined from 20.3 /fb data collected with the ATLAS detector at a center-of-mass energy of 8 TeV. The measurements are carried out with a fine granularity in the Z boson transverse momentum as well as three coarse Z rapidity intervals. The measurements are compared to precise theory calculations at NNLO in QCD and state-of-the-art MC generation at NLO in QCD. Strong discrimination power between different approaches of the QCD modeling and effects beyond NNLO are found
Speaker: Aleksei Ezhilov (B.P. Konstantinov Petersburg Nuclear Physics Institute - PNPI)
• 125
Vector boson (W, Z) studies with CMS
Run I & II electroweak studies of vector boson production
Speaker: Dr Ji Yeon Han (University of Rochester in Rochester, NY, United States)
• 126
Measurements of the production of jets in association with a W or Z boson with the ATLAS detector (WG2)
The production of jets in association with vector bosons is an important process to study QCD in a multi-scale environment. The ATLAS collaboration has performed a first measurement of vector boson+jets cross sections, differential in several kinematic variables, in 3.2 /fb of proton-proton collision data taken in 2015 at center-of-mass energies of 13TeV. In data corresponding to 20.3 /fb at a centre-of-mass energy of 8TeV, the collaboration has measured the production of vector boson+jets in the presence of a high scale defined by the transverse momentum of the leading jet, which enriches the collinear production of the gauge boson and a jet. The measurements are compared to state-of-the-art QCD calculations and Monte Carlo simulations.
Speaker: Mrs Marisa Sandhoff (Bergische Universitaet Wuppertal)
• 127
V+jets from CMS
Run I & II measurements of a vector boson (V=W, Z and photon) produced in association with jets from CMS
Speaker: Mr Fengwangdong Zhang (CERN)
• WG5 Small-x and Diffraction SR4b

### SR4b

#### DESY Hamburg

Conveners: Dr Alessia Bruni (INFN Bologna), Leszek Motyka (Jagiellonian University), Dr Rainer Schicker (Phys. Inst., Heidelberg)
• 128
Light-by-light scattering in UPC at the LHC
We will discuss diphoton semi(exclusive) production in ultraperipheral $PbPb$ collisions at energy of $\sqrt{s_{NN}}=$ 5.5 TeV (LHC). The calculation is based on equivalent photon approximation in the impact parameter space. The cross sections for elementary $\gamma \gamma \to \gamma \gamma$ subprocess are calculated including two different mechanisms: \begin{itemize} \item box diagrams with leptons and quarks in the loops and \item a vector-meson dominance (VDM-Regge) contribution with virtual intermediate hadronic (vector-like) excitations of the photons. \end{itemize} We get much higher cross sections in $PbPb$ collisions ($310$ nb) than in earlier calculation from the literature $35 \pm 7$ nb\footnote{D. d'Enterria and G.G. da Silveira, Phys. Rev. Lett. \textbf{111} (2013) 080405}. This opens a possibility to study the $\gamma \gamma \to \gamma \gamma$ (quasi)elastic scattering at the LHC. We will present many interesting differential distributions which could be measured by the ALICE, CMS or ATLAS Collaborations. We will show the range of energy $W_{\gamma\gamma}$ where elastic $\gamma \gamma$ scattering could be measured in the heavy-ion collisions. \vspace{2cm} This talk will be based on our recent paper:\\ - M. K{\l}usek-Gawenda, P. Lebiedowicz and A. Szczurek, arXiv/nucl-th:1601.07001.
Speaker: Dr Mariola Klusek-Gawenda (Institute of Nuclear Physics, Polish Academy of Sciences)
• 129
Forward $J/\psi$ production in high energy proton-nucleus collisions
Forward $J/\psi$ production and suppression in high energy proton-nucleus collisions can be an important probe of gluon saturation. We study this process in the Color Glass Condensate framework and show that using the Glauber approach to extrapolate the dipole cross section of a proton to a nucleus leads to results closer to experimental data than previous calculations in this framework. We also investigate the centrality dependence of the nuclear suppression in this model and show a comparison of our results with recent LHC data.
Speaker: Dr Bertrand Ducloue (University of Jyvaskyla)
• 130
Vector meson photoproduction in ultra-peripheral p-Pb collisions measured using the ALICE detector
The strong electromagnetic fields generated by ultra-relativistic heavy ions offer the possibility to study gamma-gamma, gamma-nucleus and gamma-proton processes at the LHC in ultra-peripheral Pb-Pb and p-Pb collisions (UPC). As exclusive photoproduction of vector mesons is sensitive to the gluon distribution of the interacting target it allows one to study saturation and shadowing phenomena. Here we report on the ALICE measurement of vector meson photoproduction in p-Pb UPC at sqrt(s_NN) = 5.02 TeV. In these asymmetric collisions, the photon is most likely coming from the Pb nucleus. As a result, the center-of-mass energy of the photon-proton system is constrained by the the rapidity of the vector meson which is measured in the laboratory frame with respect to the proton beam direction. We present the results on vector meson photoproduction in several intervals of the photon-proton center-of-mass energy.
Speaker: Jaroslav Adam (FNSPE CTU in Prague)
• 131
Ultra-Peripheral Collisions with gold ions in STAR
In 2010 and 2011, the STAR Collaboration collected a large sample of triggers for ultra-peripheral collisions.In this talk, I will present several new results involving photonuclear interactions in ultra-peripheral relativistic heavy ion collisions (UPCs). I will present an analysis of 384,000 photoproduced pion pairs, coming from rho, omega and direct pion pair production.The omega component is clearly visible through its interference with the rho peak. Measurements of the relative amplitudes of the three components will be presented, along with the phase angle between the rho and omega components. The squared momentum transfer (t) spectrum shows coherent and incoherent components. The coherent component exhibits visible diffraction minima, characteristic of the gold target nucleus. The large data sample also allows us to explore higher mass final states.I will present measurements of J/psi photoproduction and of a high-mass dipion final state.
Speaker: Dr Spencer Klein (Lawrence Berkeley National Laboratory)
• WG1 Structure Functions and Parton Densities Auditorium

### Auditorium

#### DESY Hamburg

Conveners: Dr Katarzyna Wichmann (DESY), Prof. Robert Thorne (University College London), Prof. Ronan McNulty (University College Dublin)
• 132
The Gottfried Sum Rule Revisited
Significant progress has recently been made, both experimentally and theoretically, in extracting the neutron structure function from deuterium data. Of particular note are the new CTEQ-JLab (CJ) nuclear corrections for large x PDF extraction, and the Jefferson Lab "BONUS" experiment, where a novel tagged proton spectator approach was employed to isolate the neutron target in electron-deuteron scattering. The BONUS data, combined with a wealth of precision deuterium data from Jefferson Lab, SLAC, and NMC, the latter now all with state-of-the-art CJ nuclear corrections applied, has been used to re-evaluate the Gottfried Sum rule integrand F2n-F2p. Results of this analysis will be presented, and compared with the well-known results from NMC which lacked precision neutron extraction.
Speaker: Dr Cynthia Keppel (Thomas Jefferson National Accelerator Facility)
• 133
Angular Distributions of Drell-Yan Dimuons at Fermilab Experiment 906/SeaQuest
The Lam-Tung relation, a pertubative QCD, Callan-Gross-like'' correlation of the azimuthal and polar angles of leptonic products relative to the initial hadronic plane in multiple frames, defines a standard component of any analysis using Drell-Yan as a nucleon probe. In at least three experiments involving Drell-Yan between various species of pions and nuclei at CERN and Fermilab, the existence of what appears to be (at leading-order) a double-spin flip in a single photon process manifests itself as a cosine modulation in dilepton azimuthal distributions. This modulation suggests significant non-perturbative effects, including the Boer-Mulders distribution, a nonzero correlation between the motion and spin of transversely polarized (anti)quarks within their encompassing unpolarized nucleon. Fermilab Experiment 866/NuSea saw a Lam-Tung violation in proton-induced Drell-Yan characterized by a smaller cosine dilepton azimuthal modulation relative to previous experiments conducted with pions and heavier nuclear targets with lower energy beams from the SPS at CERN. SeaQuest is investigating the difference with greater precision and at a higher x range than any previous Drell-Yan experiment. Studies of the angular distributions of dimuons in SeaQuest will be presented.
Speaker: Mr Bryan Ramson (University of Michigan)
• 134
Nuclear Effects in Deuterium and Global PDF fits
We present a detailed study of nuclear corrections in the deuteron (D) from an analysis of existing data from Deep Inelastic Scattering (DIS) off proton and D, Drell-Yan production in pp and pD interactions, $W^\pm$ and $Z$ boson production in pp and $p \bar p$ collisions. In particular, we discuss the determination of the off-shell correction describing the modification of parton distributions (PDF) in bound nucleons in the context of global PDF fits. Results are compared with the ones obtained from the study of DIS data from heavy nuclei. We also discuss the sensitivity to various models for the deuteron wave function. As an important application we discuss the impact of nuclear corrections to the deuteron on the determination of the $d$ quark distribution.
Speaker: Roberto Petti (University of South Carolina)
• 135
Double gluon distribution from the single gluon distribution
Multi parton distribution functions (MPDs) are interesting in view of the study of Multi Parton Interactions in hadron-hadron collisions. We use the Stirgling-Gaunt sum rules to construct explicitly an initial condition for the double gluon distribution function starting from the known MSTW form of the single gluon distribution function. The result is parameter free. We also consider the evolution of the distribution function with a hard scale numerically and discuss the perspective for the extension of the results to the quark sector.
Speaker: Mirko Serino (Institute of Nuclear Physics, PAN, Cracow)
• 136
Discussion
• WG4 Heavy Flavours SR2

### SR2

#### DESY Hamburg

Conveners: Mr Martijn Mulders (CERN), Maximilian Stahlhofen (DESY), Mr Mikhaylo Lisovyi (DESY/Hamburg Uni)
• 137
Top quark cross section measurements with CMS
Measurements of the inclusive and differential top quark pair production cross section at 7 TeV, 8 TeV and 13 TeV are presented, performed using CMS data collected in 2011, 2012 and 2015. The total cross section is measured in the lepton+jets, dilepton and fully hadronic channels, including the tau-dilepton and tau+jets modes. Indirect constraints on both the top quark mass and alpha_s are obtained through their relation to the inclusive cross section. First measurements of top quark pair production with additional b-quarks in the final state are also presented. Differential cross sections are measured and are given as functions of various kinematic observables, including the transverse momentum and rapidity of the (anti)top quark and the top-antitop system and the jets and leptons of the event final state. Multiplicity and kinematic distributions of the jets produced in addition to the top pair are also investigated. The results are combined and confronted with precise theory calculations.
Speaker: Mr Nazar Bartosik (DESY)
• 138
Top quark pair­production cross­section measurements with the ATLAS detector
Measurements of the inclusive and differential top­quark pair cross sections in proton­proton collisions at both 8 and 13 TeV with the ATLAS detector at the Large Hadron Collider are presented. The inclusive measurements reach high precision and are compared to the best available theoretical calculations. Differential measurements of the kinematic properties of the top quark production are also discussed. These measurements, including results using boosted tops, probe our understanding of top pair production in the TeV regime. The results, unfolded to particle and parton level, are compared to Monte Carlo generators implementing LO and NLO matrix elements matched with parton showers and NNLO QCD calculations.
Speaker: Mr Hasib Ahmed (University of Oklahoma)
• 139
Measurements of the top-quark properties in the production and decays of ttbar events at CMS
Measurements of several top-quark properties are presented, obtained from the CMS data collected at various centre-of-mass energies. The results include measurements of the top pair charge asymmetry, the W helicity in top decays, the top quark charge, the ttbar spin correlation, of the top polarisation and the search for anomalous couplings. The results are compared with predictions from the standard model as well as new physics models. The cross section of ttbar events produced in association with a W, Z boson or a photon is also measured.
Speaker: Deniz Poyraz (Ghent University in Ghent, Belgium)
• 140
Top quark pair property measurements using the ATLAS detector at the LHC
Precise measurements of the properties of the top quark test the Standard Model (SM) and can be used to constrain new physics models. The top quark pair charge asymmetry is an asymmetry predicted to occur beyond leading­order QCD in the SM, and may be significantly enhanced by the presence of new physics. The ttbar production charge asymmetry is measured inclusively and differentially using the 8 TeV ATLAS dataset using both the lepton+jets and dilepton channels, including a dedicated measurement for highly boosted top­quarks. The results are in agreement with the SM and are compared to new physics models. The top­quark is predicted in the SM to decay almost exclusively into a W boson and a b­quark. We present a wide range of searches for non­SM top quark decays using the 8 TeV ATLAS dataset, including t->q H, t->q gamma and t->q Z. In addition, measurements of the W­helicity and spin correlations in ttbar production are presented.
• WG6 Spin Physics SR4a

### SR4a

#### DESY Hamburg

Conveners: Dr Emanuele Roberto Nocera (Rudolf Peierls Centre for Theoretical Physics University of Oxford), Dr Erin Seder (CEA Saclay DSM/IRFU/SPhN/LSN), Dr Salvatore Fazio (Brookhaven National Laboratory), Dr Silvia Pisano (Laboratori Nazionali di Frascati - INFN)
• 141
Iterative Monte Carlo analysis of spin-dependent parton distributions
We present a comprehensive new global QCD analysis of polarized inclusive deep-inelastic scattering, including the latest high-precision data on longitudinal and transverse polarization asymmetries from Jefferson Lab and elsewhere. The analysis is performed using a new iterative Monte Carlo fitting technique which generates stable fits to polarized parton distribution functions (PDFs) with statistically rigorous uncertainties. Inclusion of the Jefferson Lab data leads to a reduction in the PDF errors for the valence and sea quarks, as well as in the gluon polarization uncertainty at x > 0.1. The study also provides the first determination of the flavor-separated twist-3 PDFs and the d 2 moment of the nucleon within a global PDF analysis.
Speaker: nobuo sato (jefferson lab)
• 142
Threshold resummation for polarized high-p_T hadron production at COMPASS
We study the cross section for the photoproduction process gamma N -> h X where the incident photon and nucleon are longitudinally polarized and a hadron h is observed at high transverse momentum. Specifically, we address the "direct" part of the cross section, for which the photon interacts in a pointlike way. For this contribution we perform an all-order resummation of logarithmic threshold corrections generated by soft or collinear gluon emission to next-to-leading logarithmic accuracy. We present phenomenological results relevant for the COMPASS experiment and compare to recent COMPASS data.
Speaker: Ms Claudia Uebler (University of Regensburg)
• WG7 Future Experiments SR3

### SR3

#### DESY Hamburg

Conveners: Claire Gwenlan (Oxford), Dr Elke-Caroline Aschenauer (BNL), Dr Wally Melnitchouk (Jefferson Lab)
• 143
eRHIC: an high-energy high-luminosity electron-ion collider at BNL
In this talk I present current design of our future electron-ion collider (EIC) at BNL, eRHIC. It is based on the existing Relativistic Heavy Ion Collider (RHIC) hadron facility, with two intersecting superconducting rings, each 3.8 km in circumference. We plan adding a polarized electron-beam with energy tunable within the 5-20 GeV range to collide with variety of species in the existing RHIC-accelerator complex. Specifically, the hadron species will include polarized protons (with a top energy of 250 GeV), polarized He3 ions (with a top energy of 170 GeV/u), and light and heavy fully striped ions (with energies up to 100 GeV/u). Our innovative design is based on one of the RHIC’s hadron rings and a multi-pass energy-recovery linac (ERL). Using the ERL as the electron accelerator in our collider assures high luminosity reaching above 10^34 cm^-2 s^-1, and a c.m. energy range ranging from 30 GeV to 140 GeV. We are also considering a ring-ring eRHIC design, which has lower luminosity, as a back-up option.
Speaker: Prof. Vladimir Litvinenko (Stony Brook University)
• 144
JLEIC – A High Luminosity Polarized Electron-Ion Collider at Jefferson Lab
The new NSAC Long Range Plan endorses construction of a high energy high luminosity polarized electron-ion collider in US for reaching new QCD frontier. JLEIC, a Jefferson Lab ring-ring design of electron-ion collider based on the CEBAF recirculating linac, will enable collisions of electrons with energy up to 10 GeV and either protons with energy up to 100 GeV, or heavy ions with energy up to 40 GeV/u. Both the proton beam and the light-ion beams will have high polarization above 70%. JLEIC will accommodate two physics detectors, a primary one with full acceptance and a secondary high-luminosity one with less demanding specification. By implementing the multi-phase traditional electron cooling in both the ion booster ring and the ion collider ring, ultrahigh luminosity close to 1034 cm-2s-1 per detector with large acceptance can be achieved. We will present the recent progress in the JLEIC design.
Speaker: Dr Yuhong Zhang (Jefferson Lab)
• 145
A High Energy e-p/A Collider Based on CepC-SppC
The recent proposal of CepC and SppC, the next energy frontier e+e- and pp circular colliders by IHEP, China, in a common accelerator complex, provides an opportunity to realize collisions of protons or ions with electrons or positrons in an ultra-high range of center-of-mass energy up to 4.2 TeV. This paper presents a preliminary design study of this high energy e-p/A collider based on the CepC-SppC facility. The design parameters for different operational scenarios and anticipated luminosities (up to middle of 10^33 cm^-2 s^-1) will be given. We also discuss two staging approaches to realize this collider with a low cost and at an earlier time. The both first-phase approaches will be able to cover the well-studied science program of LHeC, with a luminosity several times higher than LHeC.
Speaker: Dr Yuhong Zhang (Jefferson Lab)
• 146
The CLIC physics potential
The Compact Linear Collider (CLIC) is a multi-TeV electron-positron collider under development. It offers the potential for a rich precision physics programme, combined with sensitivity to a wide range of new phenomena. To optimise its physics output CLIC is foreseen to be built and operated in several energy stages, ranging from ~350 GeV to 3 TeV centre-of mass energy. The CLIC physics potential has been studied using full detector simulations for several centre-of-mass energies. These include Higgs production through Higgsstahlung at a few hundred GeV, allowing for the couplings and width of the Higgs boson to be determined in a model-independent way through the recoil mass technique. While originally considering only leptonic Z decays in the recoil mass measurement, it was shown recently that significantly higher precisions on the couplings can be achieved by including the hadronic decay of the Z. Operation at higher centre-of-mass energies provides large statistics for the study of the Higgs boson through the WW-fusion production process. It also offers the potential to directly measure the top Yukawa coupling. At the highest centre-of-mass energy of 3 TeV, the Higgs self-coupling can be determined with 10% precision. The complete physics program for all measurements of accessible Higgs couplings is included in combined fits. Precision measurements of top quark production in e+e- collisions will significantly enhance our knowledge of top quark properties and will give new insight in physics beyond the Standard Model. The top mass can be measured at a 50 MeV accuracy level in a well-defined mass scheme by performing a scan of the top pair production threshold. For the study of the top quark couplings to electroweak gauge bosons, form factors can be determined to 1% precision, an order of magnitude better than the full LHC programme. Recent results extend the prospects to different centre-of-mass energies and to CP violating form factors. New studies of Flavour Changing Neutral Current decays of the top quark, such as the decay t -> cH, to a branching ratio BR(t->cH) ~ 10^-5, are also presented. The search for phenomena beyond the Standard Model through direct observation of new particles and precision measurements is a main motivation for the high-energy stages of CLIC. An overview of physics benchmark studies assuming different New Physics scenarios is given. New particles can be discovered in a model-independent way almost up to the kinematic limit of sqrt(s)/2. The low background conditions at CLIC provide extended discovery potential compared to hadron colliders, for example in the case of non-coloured TeV-scale SUSY particles. In addition to studying new particles directly, BSM models can be probed up to scales of tens of TeV through precision measurements. Examples, including recent results on the reaction e+ e- -> gamma gamma, are presented. Beam polarisation allows to constrain the underlying theory further in many cases. The talk will also include a discussion of LHC results relevant for the CLIC physics case.
Speaker: Aidan Robson (Glasgow)
• 10:32 AM
Coffee break
• WG1 Structure Functions and Parton Densities Auditorium

### Auditorium

#### DESY Hamburg

Conveners: Dr Katarzyna Wichmann (DESY), Prof. Robert Thorne (University College London), Prof. Ronan McNulty (University College Dublin)
• 147
Photons and weak bosons do not interact strongly with the dense and hot medium formed in the nuclei collisions, thus should be sensitive to the nuclear modification of parton distribution functions (nPDFs). The in-medium modification of heavy Charmonium states plays an important role in studying the hot and dense medium formed in the larger collision systems. The ATLAS detector, optimized for searching new physics in proton-proton collisions, is especially well equipped to measure photons, Z, W bosons and quakonium in the high occupancy environment produced in heavy ion collisions. We will present recent results on the prompt photon, Z and W boson yields as a function of centrality, transverse momentum and rapidity, from the ATLAS experiment.
Speaker: Markus Konrad Kohler (Weizmann Institute of Science)
• 148
Comparison of the F2 Structure Function in Iron as Measured by Charged Lepton and Neutrino Probes
World data for the F2 structure function for Iron, as measured by multiple charged lepton and neutrino scattering experiments, are compared. Data obtained from charged lepton and neutrino scattering at larger values of x are in remarkably good agreement with a simple invocation of the 18/5 rule, while a discrepancy in the behavior of the data obtained from the different probes well beyond the data uncertainties is observed in the shadowing/anti-shadowing transition region where the Bjorken scaling variable x is less than 0.15. The data are compared to theoretical calculations. Details and results of the data comparison will be presented.
Speaker: Dr Keppel Cynthia (Thomas Jefferson National Accelerator Facility)
• 149
Nuclear parton distributions from the nCTEQ group
We present the nCTEQ15 global analysis of nuclear parton distribution functions (nPDFs). The main addition to the previous nCTEQ analysis is the introduction of PDF uncertainties based on a modified Hessian method. Another important improvement is the inclusion of pion production data from RHIC providing additional constraints on gluon PDF. In this presentation we briefly discuss the framework of our analysis and concentrate on the comparison of our results with those of other groups providing nPDFs. Additionally we present predictions for selected results from the LHC heavy ion collisions.
Speaker: Aleksander Kusina (LPSC Grenoble)
• 150
Nuclear Parton Distributions
We present the status of our calculation of nuclear parton distribution functions on the basis of our recently developed semi-microscopic model, which takes into account a number of nuclear effects including nuclear shadowing, Fermi motion and nuclear binding, nuclear meson-exchange currents and off-shell corrections to bound nucleon distributions. We discuss in details the dependencies of nuclear effects on the type of parton distribution (nuclear sea vs. valence) as well as on the parton flavour (isospin). We discuss a number of applications ranging from Deep Inelastic Scattering to the Drell-Yan production.
Speakers: Roberto Petti (University of South Carolina), Sergey Kulagin (INR)
• 151
Neutron-skin effect and centrality dependence of high-pT observables in nuclear collisions
High-energy nuclear collisions are often classified in terms of centrality. Theoretically the centrality binning is obtained using the Woods-Saxon parametrization for nuclear density as an input for Glauber model. Traditionally the parametrization do not differentiate between protons and neutrons. However, according to measurements in nuclear physics, the density of neutrons decrease slower at the edge of the nuclei than the density of protons. This phenomenon is known as a neutron-skin effect and can have an influence to the centrality dependence of high-pT observables sensitive to electric charge in high-energy nuclear collisions. Potentially the phenomenon could also be measured in e+A collisions if a similar centrality binning can be performed. In this talk we present NLO pQCD predictions for the centrality dependence of the direct photon production at high-pT in Pb+Pb collisions at the LHC applying the neutron-skin effect and spatially dependent nuclear PDFs from EPS09s fit. Furthermore, we discuss about W production and the ratio between positively and negatively charged hadrons. The advantage of these observables would be that the nuclear modifications of the PDFs largely cancel out allowing one to separate these two competing centrality-dependent effects.
Speaker: Dr Ilkka Helenius (Lund University)
• 152
Pion structure function from leading neutron electroproduction and SU(2) flavor asymmetry
We examine the efficacy of pion exchange models to simultaneously describe leading neutron electroproduction at HERA and the d-bar - u-bar flavor asymmetry in the proton. A detailed chi^2 analysis of the ZEUS and H1 cross sections, when combined with constraints on the pion flux from Drell-Yan data, allows regions of applicability of one-pion exchange to be delineated. The analysis disfavors several models of the pion flux used in the literature, and yields an improved extraction of the pion structure function and its uncertainties at parton momentum fractions in the pion of 4 x 10^{-4} < x_pi < 0.05 at a scale of Q^2=10 GeV^2. Based on the fit results, we provide estimates for leading proton structure functions in upcoming tagged deep-inelastic scattering experiments at Jefferson Lab on the deuteron with forward protons.
Speaker: Dr Wally Melnitchouk (Jefferson Lab)
• WG2 QCD and Hadronic Final States SR1 (DESY, Hamburg)

### SR1

#### DESY, Hamburg

Conveners: Frank Tackmann (DESY), Dr Shima Shimizu (Kobe University), Dr Simon Plätzer (DESY Theory Group)
• 153
Status and Perspectives of NNLO plus Parton Shower Matching
Review of NNLO+PS
Speaker: Dr Simone Alioli (CERN)
• 154
Factorization and resummation for massive quark effects in exclusive Drell-Yan
Exclusive 0-jet processes at hadron colliders are nowadays studied at an unprecedented precision in theory and experiment. Within the framework of Soft-Collinear Effective Theory we discuss how to incorporate massive bottom quark effects in the resummed cross section for Drell-Yan, where as specific examples for a measured exclusive observable we consider the transverse momentum of the electroweak boson and beam thrust. At NNLL' order, i.e. including matrix elements at O(alphas^2) and NNLL resummation, one has to account for both heavy quark initiated (primary) corrections to the hard scattering process as well as secondary radiation effects. The theoretical description depends on the hierarchy between the involved scales, ranging from the decoupling limit for large masses to the massless limit for small masses, and involves quark mass dependent beam functions/TMDs and soft functions in between.
Speaker: Piotr Pietrulewicz (DESY)
• 155
NLL soft gluon resummation for associated ttH production
In this talk a short description of the soft gluon resummation for pp->ttbarH process will be given. This is the first application of the Mellin resummation technique in a 2->3 process. The absolute threshold resummation is performed up to NLL accuracy and matched to the known NLO QCD cross-section. Results for the total cross-section at the LHC and their theoretical uncertainties will be presented.
Speaker: Mr Tomasz Stebel (Jagiellonian University)
• 156
Attacking one-loop multi-leg Feynman integrals with the Loop-Tree Duality method
We present a first numerical implementation of the Loop-Tree Duality (LTD) method for the direct numerical computation of multi-leg one-loop Feynman integrals. We discuss in detail the singular structure of the dual integrands and define a suitable contour deformation in the loop three-momentum space to carry out the numerical integration. Then, we apply the LTD method to the computation of ultraviolet and infrared finite integrals, and present explicit results for scalar integrals and tensor integrals with up to six legs (hexagons). The LTD method exhibits an excellent performance independently of the number of external legs.
Speaker: Dr Grigorios Chachamis (IFT UAM-CSIC)
• WG3 Electroweak Physics and Beyond the Standard Model SR4b

### SR4b

#### DESY Hamburg

Conveners: Dr Alexis Kalogeropoulos (DESY), Prof. Kevin Black (Boston University)
• 157
Dark Matter searches with Mono-X signatures at the ATLAS experiment
At the LHC dark matter particles can be produced in association with other particles which mainly come from initial state radiation. Searches for such processes are presented using events with jets, photons or massive gauge bosons recoiling against large missing transverse momentum in ATLAS at 13 TeV. These “mono-X” signatures provide powerful probes to dark matter production at the LHC, allowing to interpret results in terms of simplified models with pair production of WIMPs.
Speaker: Emma Elizabeth Tolley (Harvard University)
• 158
Searches for BSM physics in diphoton final state at CMS
Many physics scenarios beyond the standard model predict the existence of heavy resonances decaying to diphotons. This talk presents searches for BSM physics in the diphoton final state at CMS, focusing on the recent results obtained using data collected at the LHC in 2015.
Speaker: Milena Eleonore Quittnat (Institute for Particle Physics, ETH Zürich in Zürich, Switzerland)
• 159
Searches for new physics in high-mass fermionic final states and jets with the ATLAS detector at the LHC
Many new physics scenarios beyond the Standard Model predict resonant or non-resonant production of high-transverse momentum fermions or gluons. The high-mass resonant production of bottom-quark pairs is also a good benchmark process for high-pT b-quark tagging. This talk summarizes Run 2 searches for new physics in fermionic final states and jets at the ATLAS experiment in LHC.
Speaker: Mr Oleksandr Viazlo (Lund University)
• 160
Searches for dark matter at CMS
Many theories predict candidates to the dark matter particles that are light enough to be produced at the LHC. This talk presents the searches for dark matter at CMS, focusing on the recent results obtained using data collected in 2015.
Speaker: Phat Srimanobhas (Chulalongkorn University in Bangkok, Thailand)
• 161
Searches for BSM physics in dilepton, multilepton, and lepton+MET final states at CMS
Many physics scenarios beyond the standard model predict the existence of new particles decaying to dilepton, multilepton, and lepton+MET final states. This talk presents searches for BSM physics in these three final states at CMS, focusing on the recent results obtained using data collected at the LHC in 2015.
Speaker: Laurent Thomas (University of Florida in Gainesville, FL, United States)
• WG4 Heavy Flavours SR2

### SR2

#### DESY Hamburg

Conveners: Mr Martijn Mulders (CERN), Maximilian Stahlhofen (DESY), Mr Mikhaylo Lisovyi (DESY/Hamburg Uni)
• 162
Relation between the on-shell and $\overline{\rm MS}$ mass at four loops
In this talk the relation between heavy quark masses defined in the on-shell and $\overline{\rm MS}$ scheme is discussed at four-loop order in QCD. Special emphasis is put on the top quark mass where the four-loop result is used to estimate the remaining renormalon uncertainty. The relation between the $\overline{\rm MS}$ and on-shell mass can also be used to establish precise relations between so-called threshold masses and the $\overline{\rm MS}$ mass which has important applications both for bottom and top.
Speaker: Prof. Matthias Steinhauser (KIT)
• 163
Measurements of the top quark mass using the ATLAS detector at the LHC
The latest measurements of the top quark mass using the ATLAS experiment are presented. A measurement based on a multi­dimensional template fit that can constrain the uncertainties on the energy measurements of jets is presented and combined with a measurement using dilepton events. A new measurement of the top quark mass using leptonic kinematic variables is presented. The measurement uses a novel technique to measure the top quark mass with minimal dependence on hadronic jets. In addition, measurements are presented that use precision theoretical QCD calculations for both inclusive ttbar production and ttbar production with an additional jet to extract the top quark mass in the pole­mass scheme.
Speaker: Michael Bender (LMU München)
• 164
Top quark mass measurements with CMS
Measurements of the top quark mass are presented, obtained from CMS data collected in proton proton collisions at the LHC at centre-of-mass energies of 7 TeV and 8 TeV. The mass of the top quark is measured using several methods and channels, including the reconstructed invariant mass distribution of the top quark, an analysis of endpoint spectra as well as measurements from shapes of top quark decay distributions. The dependence of the mass measurement on the kinematic phase space is investigated. The results of the various channels are combined and compared to the world average. The top mass and also alpha_s are extracted from the top pair cross section measured at CMS.
Speaker: Mr Simon Spannagel (DESY - CMS)
• 165
Complete off-shell effects for top-antitop + jet production with leptonic decays at the LHC
We present results for the NLO QCD corrections to the process $pp \to t\bar{t} j \to W^+W^-b\bar{b} j \to e^+ \nu_e \mu^- \bar{\nu}_\mu b \bar{b} j + X$, including for the first time the full off-shell effects for top quarks and W bosons: double-, single- and non-resonant contributions at the order {\cal{O}}(\alpha_{s}^4 \alpha^4). Focusing on the case of the LHC at 8 TeV, we analyse numerical results for the total cross section and its scale dependence, and show differential distributions. We also provide an estimate of the impact of the off-shell effects within our study.
Speaker: Dr Giuseppe Bevilacqua (University of Debrecen)
• 166
Determination of the top-quark mass from single top-quark production in hadronic collisions
We determine the mass of the top quark from cross section data for the hadro-production of single top quarks in the $t$- and $s$-channel reactions. We apply QCD perturbative corrections up to next-to-next-to-leading order terms from soft-gluon resummation to extract the top-quark mass in well-defined renormalization schemes. The cross section for the production of single top quarks is dominated by the light quark-flavor distributions in the proton, which allows for a mass determination largely independent of the gluon distribution.
Speaker: Dr Stephan Thier (Universität Hamburg)
• 167
Top quark mass calibration for Monte-Carlo event generators
The lack of knowledge how the top quark mass parameter in Monte-Carlo event generators (MCs) is related to field theoretically defined mass schemes limits the theoretical interpretation of the top quark mass measurements based on templates obtained from direct reconstruction analyses at hadron colliders. In the first part of the talk I review the conceptual aspects of the problem and argue which classes of field theoretic heavy quark mass definitions have a close relation to the quark mass parameter in MCs. In the second part I describe a method to calibrate the top quark MC mass parameter by fits of MC hadron level predictions for observables with very strong mass sensitivity to corresponding hadron level QCD predictions. I demonstrate the approach for thrust in electron positron collisions using factorization based QCD calculations at NNLL / NLO that account for hadronization and the complete top mass dependence, and I present concrete numerical results.
Speaker: Prof. Andre Hoang (University of Vienna)
• WG6 Spin Physics SR4a

### SR4a

#### DESY Hamburg

Conveners: Dr Emanuele Roberto Nocera (Rudolf Peierls Centre for Theoretical Physics University of Oxford), Dr Erin Seder (CEA Saclay DSM/IRFU/SPhN/LSN), Dr Salvatore Fazio (Brookhaven National Laboratory), Dr Silvia Pisano (Laboratori Nazionali di Frascati - INFN)
• 168
Final results on the spin dependent structure function g_1^d from COMPASS
The COMPASS experiment at CERN SPS has taken data with a polarised muon beam scattering off a polarised LiD target from 2002-2004. The same measurement was also performed in 2006 increasing the statistics by roughly a factor of two. The new results from 2006 data on the longitudinal double spin asymmetry A_1^d on the spin dependent structure function g_1^d will be shown and compared to the previous results from 2002-2004. Using the combined data set the first moment of g_1^d is calculated. This quantity is used to calculate the singlet axial charge a_0, which is equal to Delta Sigma in the MSbar scheme. Using also the axial charges a_3 and a_8 the first moments of the quark helicity distributions are obtained. In addition the influence on the Bjorken sum rule will be discussed. Supported by BMBF and GRK Symmetry Breaking (DFG/GRK 1581)
Speaker: Mr Malte Wilfert (Johannes-Gutenberg-Universitaet Mainz)
• 169
The spin structure of the proton at low x and low Q2 in two-dimensional grids from COMPASS
The longitudinal double spin asymmetries A1p and the spin dependent structure function of the proton g1p were extracted from COMPASS data in the region of low x and low Q2. The data were taken on 2007 and 2011 from scattering of polarised muons off polarised protons, resulting in a sample that is 150 times larger than the one from the previous experiment SMC that pioneered searches in this kinematic region. For the first time, A1p and g1p were evaluated in this region in two-dimensional grids of kinematic variables: (x,Q2), (ν,Q2), (x,ν) and (Q2,x). The following kinematic region was investigated: 4.0x10-5<x<4.0x10-2, 0.001<Q2<1 (GeV/c)2 and 14<ν<194 GeV. The obtained results can be confronted with theoretical models.
Speaker: Ana Sofia Nunes (LIP-Lisbon)
• 170
Measurement of double helicity asymmetries ($A_{LL}$) in $\pi^{0}$ and $\pi^{\pm}$ production at mid-rapidity in longitudinally polarized $p+p$ collisions at $\sqrt{s}$ = 510 GeV with PHENIX experiment
One of the main goals of the RHIC spin program is the determination of the gluon helicity contribution to the proton spin. This can be accessed by measuring double spin asymmetries ($A_{LL}$) of pion production at mid-rapidity in longitudinally polarized proton collisions with the PHENIX experiment. The ordering of the asymmetries with the charge of the final state pions can in addition directly infer the sign of the gluon spin contribution. Charged and neutral pions are reconstructed in the central PHENIX tracking system and electromagnetic calorimeters, respectively. The asymmetries are evaluated between collisions of bunches with the same and opposite helicity after correcting for differences in luminosity and for beam polarizations. The $A_{LL}$ measurements of pion production at $\sqrt{s}$ = 200 GeV have been published previously. To extend our understanding of the gluon polarization to a lower gluon momentum fraction ($x$), high statistics data was collected at a higher $\sqrt{s}$ = 510 GeV in 2012-2013. We present the recently published $\pi^{0}$ production results and the status of the $\pi^{\pm}$ $A_{LL}$ measurements at mid-rapidity at $\sqrt{s}$ = 510 GeV. The neutral pion result confirms a positive contribution of the gluon spins to the proton spin for $x >$ 0.05 and provides additional constraints on the gluon polarization down to $x \sim$ 0.01.
Speaker: Ralf Seidl (RIKEN)
• 171
Probing Gluon Helicity with Dijets from √s = 510 GeV Polarized Proton Collisions at STAR
The production of jets in polarized proton collisions at STAR is dominated by quark-gluon and gluon-gluon scattering processes. The dijet longitudinal double-spin asymmetry (A_LL) is sensitive to the polarized parton distributions and may be used to extract information about the gluon helicity contribution (ΔG) to the spin of the proton. Previous STAR jet measurements at √s = 200 GeV show evidence of polarized gluons for gluon momentum fractions above 0.05. The measurement of dijet A_LL at √s = 510 GeV will extend the current constraints on ΔG to lower gluon momentum fractions and allow for the reconstruction of the partonic kinematics at leading order. Preliminary results from the dijet A_LL measurements from ~80 pb^(-1) of ~53% polarized proton data taken during the 2012 RHIC run will be presented.
Speaker: Suvarna Ramachandran (STAR Collaboration, University of Kentucky)
• 172
\bf Measurement of $W^{\pm}$ single spin asymmetries and $W$ cross section ratio in polarized $p+p$ collisions at $\sqrt{s}=510$ GeV at STAR
The STAR experiment at RHIC has provided significant contributions to our understanding of the structure of the proton. The STAR experiment is well equipped to measure $W^\pm \rightarrow e^\pm + \nu$ in $\sqrt{s}=510$ GeV longitudinally polarized $p+p$ collisions at mid-rapidity ($|\eta|<1$). W single-spin asymmetries, $A_L$, measured as a function of decay positron (electron) pseudo-rapidity $\eta$ for $W^+ (W^-)$ are sensitive to the individual helicity polarizations of $u$ and $\bar{d}$ ($d$ and $\bar{u}$) quarks. Due to maximal violation of parity, during the production, $W$ bosons couple to left-handed quarks and right-handed anti-quarks and hence offer direct probes of their respective helicity distributions in the nucleon. The published STAR $A_L$ results (combination of 2011 and 2012 data) have been used by several theoretical analyses suggesting a significant impact in constraining the helicity distributions of anti-$u$ and anti-$d$ quarks. In 2013 STAR collected a large sample of data at $\sqrt{s}=510$ GeV with a total integrated luminosity of $\sim$300 pb$^{-1}$ with an average beam polarization of $\sim$54\%. This resulted in an increase of a factor 3 in the figure of merit compared to the dataset used for previous analyses. The status of the analysis of the STAR 2013 W $A_L$ will be presented along with the future plans for final W $A_L$ results by combining both STAR 2012 and 2013 data of total integrated luminosity of about $\sim$400 pb$^{-1}$. \\ W cross section ratio ($W^+ / W^-$) measurements at STAR are sensitive to unpolarized u, d, $\bar{u}$, and $\bar{d}$ quark distributions. At these kinematics, STAR is able to measure the quark distributions near Bjorken-x values of 0.1. The increased statistics will lead to a higher precision measurement of the $W^+ / W^-$ cross section ratio as well as allow for a measurement of its $\eta$ dependence at mid-rapidity. An update of the W cross section ratio analysis from the STAR 2011, 2012 and 2013 runs is presented.
Speaker: Prof. Bernd Surrow (Temple University)
• WG7 Future Experiments SR3

### SR3

#### DESY Hamburg

Conveners: Claire Gwenlan (Oxford), Dr Elke-Caroline Aschenauer (BNL), Dr Wally Melnitchouk (Jefferson Lab)
• 173
A dedicated eRHIC detector design
The 2015 Long Range Plan for Nuclear Science in the US recommended a high-energy high-luminosity polarized Electron-Ion Collider as the highest priority for new facility construction following the completion of presently ongoing projects. The main physics topics to be explored at this new facility are (i) the polarized sea quark and gluon distributions in the nucleon, (ii) QCD dynamics of the low-x, high density gluon regime, (iii) hadronization in the vacuum and the nuclear medium [1]. One of the considered construction options is the addition of a high-energy polarized electron beam to the existing RHIC hadron machine, converting it into an Electron-Ion Collider (eRHIC) [2]. A dedicated eRHIC detector, designed to efficiently register and identify deep inelastic electron scattering (DIS) processes in a wide range of center-of-mass energies available with the new collider is one of the key elements of such an upgrade. The progress on the detector design work will be shown, and the new simulation results will be presented. [1] A. Accardi et al., "Electron Ion Collider: The Next QCD Frontier - Understanding the glue that binds us all" (EIC White Paper), arXiv:1212.1701v3 (2014). [2] E.C. Aschenauer et al., "eRHIC design study (An Electron-Ion Collider at BNL)", arXiv:1409.1633 (2014).
Speaker: Dr Alexander Kiselev (Brookhaven National Lab)
• 174
The path through sPHENIX and fsPHENIX toward an EIC detector at eRHIC
eRHIC is one of the options proposed as a high luminosity, polarized Electron-Ion Collider (EIC) that is based on using one of the RHIC hadron rings and a multipass Energy Recovery Linac. A beam of polarized electrons with an energy up to 21 GeV would collide with a variety of ion species, from polarized protons with a top energy of 250 GeV to fully-stripped uranium ions with energies up to 100 GeV/u. It will allow for covering a center-of-mass energy range up to 145 GeV for polarized e+p, and up to 90 GeV for e+A (for large A) collisions. One of the possible detectors to perform precision studies of the partonic structure of hadronic matter will be an upgraded PHENIX detector. The path will lead through the detector that will be built around the BaBar magnet, sPHENIX, with its components at midrapidity |$\eta$|<1 followed by an sPHENIX-Forward upgrade and additional modifications specific to the successive EIC detector. We will discuss the approach that leads to that EIC detector and present goals and requirements for a broad set of measurements from day-1 of eRHIC.
Speaker: Dr Klaus Dehmelt (Stony Brook University)
• 175
JLEIC forward detector design and performance
The Electron-Ion Collider (EIC) is envisioned as the next-generation U.S. facility to study quarks and gluons in strongly interacting matter. The broad physics program of the EIC aims to precisely image gluons in nucleons and nuclei and to reveal the origin of the nucleon spin by colliding polarized electrons with polarized protons, polarized light ions, and heavy nuclei at high luminosity. The Jefferson Lab EIC (JLEIC) design is based on a figure-8 shaped ring-ring collider. The luminosity, exceeding 10^33 cm⁻²s⁻¹ in a broad range of the center-of-mass (CM) energy and maximum luminosity above 10^34 cm⁻²s⁻¹, is achieved by high-rate collisions of short small-emittance low-charge bunches made possible by high-energy electron cooling of the ion beam and synchrotron radiation damping of the electron beam. The polarization of light ion species (p, d, ^3He) can be easily preserved and manipulated due to the unique figure-8 shape of the collider rings. The focus of this presentation is put on the forward detection capabilities of the JLEIC primary detector designed to provide essentially full acceptance to all fragments produced in collisions. The forward hadron detection is done in three stages: (1) fragments with scattering angles down to a few degree are detected in a 2m long end-cap, (2) fragments up to a few degree are detected after passing through a 1m long 2Tm spectrometer dipole in front of the final focusing quads (FFQs), and (3) fragments up to about one degree pass through the apertures of the FFQs and are detected in a 4m space before and a 16m space after a second 4m long 20Tm spectrometer dipole. On the forward electron side, the large-angle reaction products are detected in the second end-cap. Electron scattered at small angles are detected in a low-Q^2 tagger consisting of large-aperture electron FFQs and a spectrometer dipole with a few meters of instrumented space on either side. The combination of a high luminosity, highly polarized lepton and ion beams, and detectors fully integrated with the accelerator will allow JLEIC a unique opportunity to make breakthroughs in the investigation of the strong interaction.
Speaker: Dr Rik Yoshida (JLab)
• 176
Next-generation nuclear DIS with spectator tagging at EIC
An Electron-Ion Collider (EIC) would enable next-generation measurements of DIS on light nuclei (deuteron, 3He, ...) with detection of nucleons and fragments in the forward region and measurement of their recoil momentum ("spectator tagging"). Such experiments allow one to control the nuclear configuration during the high-energy process and could be used for (a) precision measurements of neutron spin structure using in electron-deuteron DIS with proton tagging, eliminating nuclear binding through on-shell extrapolation in the recoil momentum; (b) controlled measurements of the nuclear modifications of quark/gluon densities (EMC effect) in defined nuclear configurations; (c) novel studies of diffraction and nuclear shadowing at x << 0.1. We review the physics applications of spectator tagging at EIC, summarize the experimental and theoretical challenges, and report process simulations and physics impact studies from a dedicated R&D project.
Speaker: Wim Cosyn (Ghent University)
• 177
The Detector Design of the Jefferson Lab EIC
The Electron-Ion Collider (EIC) is envisioned as the next-generation U.S. facility to study quarks and gluons in strongly interacting matter. The broad physics program of the EIC aims to precisely image gluons in nucleons and nuclei and to reveal the origin of the nucleon spin by colliding polarized electrons with polarized protons, polarized light ions, and heavy nuclei at high luminosity. The Jefferson Lab EIC (JLEIC) design is based on a figure-8 shaped ring-ring collider. The luminosity, exceeding 10^33 cm⁻²s⁻¹ in a broad range of the center-of-mass energy and maximum luminosity above 10^34 cm⁻²s⁻¹, is achieved by high-rate collisions of short small-emittance low-charge bunches made possible by high-energy electron cooling of the ion beam and synchrotron radiation damping of the electron beam. The polarization of light ion species (p, d, ^3He) can be easily preserved and manipulated due to the unique figure-8 shape of the collider rings. The focus of this presentation is put on the JLEIC primary detector that has been designed to support the full physics program of the EIC and to provide essentially full acceptance to all fragments produced in collisions. The detector has been fully integrated with the accelerator and extended to the forward electron and hadron regions to achieve exceptional small-angle acceptance and resolution as well as high-precision electron polarimetry and low-Q^2 tagging. The central-detector design allows for excellent tracking up to small angles and excellent hadron PID resulting and offers a great performance, in particular for semi-inclusive and exclusive measurements. The combination of high luminosity, highly polarized lepton and ion beams, and a full acceptance, multi-purpose detector fully integrated with the accelerator will allow JLEIC a unique opportunity to make breakthroughs in the investigation of the strong interaction.
Speaker: Dr Markus Diefenthaler (Jefferson Lab)
• 1:00 PM
Lunch break
• WG2 QCD and Hadronic Final States SR1

### SR1

#### DESY Hamburg

Conveners: Frank Tackmann (DESY), Dr Shima Shimizu (Kobe University), Dr Simon Plätzer (DESY Theory Group)
• 178
Recent development in parton shower multijet merging
Review of multijet merging.
Speaker: Dr Johannes Bellm (IPPP, Durham Unviversity)
• 179
Overview of High Energy Jets
High Energy Jets (HEJ) is a novel method for organising the resummation of high energy logs in QCD to Leading Logarithmic accuracy (LL) in multi-jet production at hadronic colliders. In this talk, I will introduce the main concepts behind the approach and show how we build our exclusive predictions. I will show important results from recent LHC jet analyses. I will then discuss how the formalism can be extended to include Next-to-Leading Log (NLL) before focussing on recent work on including full finite quark mass effects in Higgs production in association with dijets.
Speaker: James Cockburn (University of Edinburgh)
• 180
Multi-jet production and jet correlations at CMS
Hadronic jet production at LHC is an excellent testing ground for QCD. Essential components of QCD, necessary for the description of hadronic jet data, are hard parton radiation and multiple parton interactions. The importance of these components increases for final states including multiple jets. We will show results of one observables sensitive to the hard parton radiation, which is the azimuthal correlation between jets. Measurements of multi-jet production in specific topologies is particularly sensitive to multiple parton interactions. In this report measurements of multi-jet production performed with the CMS detector at LHC with pp collision data are summarized.
Speaker: Gabor Veres (CERN)
• 181
Measurement of 4-jet production cross sections and transverse energy correlations with the ATLAS detector
The production of multi-jet final states at hadron colliders probes pQCD at several mass scales. The processes can also be used to probe the gluon density function of the proton. The ATLAS collaboration has measured the production of 4-jets final states in in 20.3 /fb of data collected at a center-of-mass energy of 8TeV. The measurements have been performed differentially as a function of a variety of kinematic and topological observables and compared with state-of-the-art theory calculations at NLO in pQCD and with the predictions of several MC generators. The collaboration has also used multi-jets events in data taken at an effective integrated luminosity of 158 /pb at a center-of-mass energy of 7TeV to measure the transverse energy correlation and its asymmetry and derive a measurement of the strong coupling constant.
Speaker: Melissa Ridel (LPNHE-Paris)
• WG1/WG3 joint session (EW+PDF) Auditorium

### Auditorium

#### DESY Hamburg

Conveners: Dr Katarzyna Wichmann (DESY), Prof. Kevin Black (Boston University), Prof. Robert Thorne (University College London), Prof. Ronan McNulty (University College Dublin), Prof. Sanjay Padhi (Brown University), Prof. Shufang Su (University of Arizona)
• 182
Measurements of inclusive and differential Drell-Yan cross sections with the ATLAS detector (WG1)
Precision measurements of the Drell-Yan production of W and Z/gamma* bosons at the LHC provide a benchmark of our understanding of perturbative QCD and probe the proton structure in a unique way. The ATLAS collaboration has performed high precision measurements at center-of-mass energies of 7TeV and 8TeV, integrated and as a function of the rapidity and the Z/gamma* mass. New measurements at 7 TeV reach unprecedented accuracy in the resonance regions, while the 8 TeV measurements explore the high mass Z/gamma* domain. The measurements are compared to state-of-the-art calculations at NNLO in QCD, combined with various contemporary parton distribution functions and including higher-order electroweak effects. Strong constraints on the parton distribution functions are found.
Speaker: Elena Yatsenko (DESY)
• 183
Measurements of inclusive W and Z cross sections at 13 TeV with the ATLAS detector (WG1)
Precision measurements of the Drell-Yan production of W and Z bosons at the LHC provide a benchmark of our understanding of perturbative QCD and electroweak processes and probe the proton structure in a unique way. The ATLAS collaboration has performed these measurements at a center-of-mass energy of 13 TeV. Ratios of W and Z cross sections and of the W boson charges significantly reduce experimental uncertainties. In addition, ratios of the cross sections for the production of single Z bosons and top-quark pairs have been derived at various center-of-mass energies. The measurements are compared to state-of-the-art calculations at NNLO in QCD, combined with various contemporary parton distribution functions and including higher-order electroweak effects.
Speaker: Dr Hayk Pirumov (DESY)
• 184
Fit of electroweak parameters in polarized deep-inelastic scattering using data from the H1 experiment
Using inclusive DIS cross sections measured with the H1 experiment at HERA, electroweak parameters of the Standard Model are probed. The cross sections were determined using longitudinally polarized lepton beams, which enhances the sensitivity to the vector couplings of the light quarks. The quark couplings and the electroweak mixing angle are probed through the γ/Z interference. This gives access to electroweak parameters in t-channel exchange at virtualities up to 10000 GeV2.
Speaker: Daniel Britzger (DESY)
• 185
Combined QCD and electroweak analysis of HERA data
A simultaneous fit of parton distribution functions (PDFs) and electroweak parameters to HERA data on deep inelastic scattering is presented. The input data are the neutral current and charged current inclusive cross sections which were previously used in the QCD analysis leading to the HERAPDF2.0 PDFs. In addition, the polarisation of the electron beam was taken into account for the ZEUS data recorded between 2004 and 2007. Results on the vector and axial-vector couplings of the Z boson to u- and d-type quarks, on the value of the electroweak mixing angle and the mass of the W boson are presented. The values obtained for the electroweak parameters are in agreement with Standard Model predictions. The resulting sets of PDFs, ZEUS-EW, are in agreement with HERAPDF2.0 and give a good description of ZEUS data with polarisation taken into account.
Speaker: Mr Volodymyr Myronenko (DESY)
• 186
W, Z and top production measurements at LHCb
LHCb's unique forward acceptance allow for measurements of EW and hard QCD processes at large rapidity. In this talk the latest LHCb results on W, Z and top production are presented.
• WG4 Heavy Flavours SR4a

### SR4a

#### DESY Hamburg

Conveners: Mr Martijn Mulders (CERN), Maximilian Stahlhofen (DESY), Mr Mikhaylo Lisovyi (DESY/Hamburg Uni)
• 187
Single Top quark production cross section using the ATLAS detector at the LHC
Measurements of single top­quark production in proton proton collisions are presented. The measurements include the first such measurements from the 13 TeV ATLAS dataset. In the leading order process, a W boson is exchanged in the t­channel. The single top­quark and anti­top total production cross sections, their ratio, as well as a measurement of the inclusive production cross section is presented. At 8 TeV, differential cross­section measurements of the t­channel process are also presented, these measurements include limits on anomalous contributions to the Wtb vertex. A measurement of the production cross section of a single top quark in association with a W boson, the second largest single­top production mode, is also presented. Finally, evidence for single­top production in the 8 TeV ATLAS dataset is presented. All measurements are compared to state­of­ the­art theoretical calculations.
Speaker: Mr Patrick Rieck (Humboldt-University of Berlin)
• 188
Single top quark production with CMS
Measurements of single top quark production are presented, performed using CMS data collected in 2011, 2012 and 2015 at centre-of-mass energies of 7, 8 and 13 TeV respectively. The cross sections for the electroweak production of single top quarks in the t-channel and in association with W-bosons is measured and the results are used to place constraints on the CKM matrix element Vtb. In the t-channel the ratio of top and anti-top production cross sections is determined and compared with predictions from different parton density distribution functions. In the same channel, the inclusive cross-section in the fiducial volume is also measured. Measurements of top quark properties in single top quark production are also presented, such as the top-quark polarisation, the probe of tWb vertex through the W-helicity measurement in top quark decay and the searched for anomalous couplings to gluons, photons or Z bosons. A search for the s-channel is also performed.
Speaker: Soureek Mitra (Tata Institute of Fundamental Research in Mumbai, India)
• 189
Measurements of ttbar+X using the ATLAS detector
The large centre­of­mass energy available at the proton­proton collider LHC allows for the copious production of top quark pairs in association with other final state particles at high transverse momentum. The ATLAS experiment has measured several final state observables that are sensitive to additional radiation in top anti­top quark final states. Results on the top production in association with W and Z bosons at both 8 and 13 TeV are presented along with measurements of the cross section for production with an associated isolated photon at 8 TeV. Analyses probing the top pair production with additional QCD radiation include the multiplicity of jets for various transverse momentum thresholds in the 13 TeV data. These measurements are compared to modern Monte Carlo generators based on NLO QCD matrix element or LO multi­leg matrix elements.
Speaker: Alexander Khanov (Oklahoma State)
• 190
Top quark event modelling and generators in CMS
State-of-the-art theoretical predictions accurate to next-to-leading order QCD interfaced with Pythia8 and Herwig++ event generators are tested by comparing the unfolded ttbar differential data collected with the CMS detector at 8 TeV. These predictions are also compared with the underlying event activity distributions in ttbar events using CMS proton-proton data collected in 2015 at a center of mass energy of 13 TeV.
Speaker: Bugra Bilin (Middle East Technical University, Physics Department in Ankara, Turkey.)
• WG5 Small-x and Diffraction SR4b

### SR4b

#### DESY Hamburg

Conveners: Dr Alessia Bruni (INFN Bologna), Leszek Motyka (Jagiellonian University), Dr Rainer Schicker (Phys. Inst., Heidelberg)
• 191
J/Psi Production in Ultra-Peripheral Collisions at STAR
In 2010, the STAR Collaboration collected a large sample of triggers for ultra-peripheral AuAu collisions. In this talk, I will present measurements from this sample of J/Psi production in association with neutrons from photonuclear breakup. Preliminary results for the cross section as a function rapidity and pT will be presented and compared to models; the large component at low pT demonstrates the coherent production of J/Psi off the Au nuclei. In 2015, STAR also collected a sample of J/Psi mesons in ultra- peripheral pp and pAu collisions, where the protons were transversely polarized. The final state proton(s) were measured in the STAR Roman Pot system, constraining the kinematics of the process. I will present the prospects for measuring the asymmetry of J/Psi production with this sample. A non-zero asymmetry would be the first measure of the generalized parton distribution E for gluons, which is connected with the orbital angular momentum of partons in the nucleon.
Speaker: Dr William Schmidke (BNL)
• 192
Coherent J/psi photoproduction in ultra-peripheral PbPb collisions at 2.76 TeV and prospects at CMS for Run 2
The coherent J/psi photoproduction cross section is measured in ultra-peripheral PbPb collisions at 2.76 TeV at the CMS experiment at the LHC. The J/psi mesons are reconstructed via their decay into muon pairs. In this talk, the measurement of the coherent J/psi photoproduction cross section as well as the neutron dependence break-up mode ratios for this process will be presented. These measurements extend the recent ALICE results on coherent J/psi photoproduction to a new rapidity range, confirming the experimental evidence of nuclear gluon effects in gamma+Pb interactions at unprecedentedly low Bjorken-x values in the Pb nucleus. The prospects of photon-induced measurements with heavy ions using the run 2 data at the LHC will be also described.
Speaker: Daniel Tapia Takaki (The University of Kansas in Lawrence, KS, United States)
• 193
Ultra-Peripheral J/Psi Production at Forward Rapidities in Pb-Pb Interactions
Ultra-Peripheral Pb-Pb collisions, in which the two nuclei pass close to each other but at an impact parameter greater than the sum of their radii, provide information about the initial state of nuclei. In particular, J/psi production in such collisions proceeds by photon-gluon interactions, and gives access to nuclear PDFs. The ALICE collaboration has published measurements of UPC J/Psi production in LHC Run 1 in the rapidity range -4.0 < y < -2.5, and has obtained a substantially larger data set in 2015 from LHC Run 2. In this talk, the latest available results will be given.
Speaker: Ms Katie Graham (University of Birmingham)
• WG6/WG7 joint session (spin+future exp.) SR2

### SR2

#### DESY Hamburg

Conveners: Claire Gwenlan (Oxford), Dr Elke-Caroline Aschenauer (BNL), Dr Emanuele Roberto Nocera (Rudolf Peierls Centre for Theoretical Physics University of Oxford), Dr Erin Seder (CEA Saclay DSM/IRFU/SPhN/LSN), Dr Salvatore Fazio (Brookhaven National Laboratory), Dr Silvia Pisano (Laboratori Nazionali di Frascati - INFN), Dr Wally Melnitchouk (Jefferson Lab)
• 194
TMD studies with a fixed-target experiment using the LHC beams
We report on the opportunities for spin physics and Transverse-Momentum Dependent distribution (TMD) studies at a future multi-purpose fixed-target experiment using the proton LHC beams extracted by a bent crystal or using an internal gas target. The LHC multi-TeV beams allow for the most energetic fixed-target experiments ever performed, opening new domains of particle and nuclear physics and complementing that of collider physics, in particular that of RHIC and the EIC projects. The luminosity achievable with AFTER@LHC surpasses that of RHIC by more that 3 orders of magnitude in a similar energy region. In unpolarised proton-proton collisions, AFTER@LHC allows for measurements of TMDs such as the Boer-Mulders quark distributions, the distribution of unpolarised and linearly polarised gluons in unpolarised protons. Using polarised targets, one can measure transverse single-spin asymmetries (SSA) of quark and gluon sensitive probes, such as, respectively, Drell-Yan pair and quarkonium production. The fixed-target mode has the advantage to allow for measurements in the target-rapidity region, namely at large x in the polarised nucleon. We will present figures-of-merit for Drell-Yan SSA and prospects for SSA for gluon sensitives probes.
Speaker: Jean-Philippe Lansberg (IPN Orsay - Paris Sud U. - CNRS/IN2P3)
• 195
The RHIC Cold QCD Plan for 2017 to 2023: A Portal to the EIC
The exploration of the fundamental structure of strongly interacting matter has always thrived on the complementarity of lepton scattering and purely hadronic probes. As the community eagerly anticipates a future electron ion collider (EIC) in the U.S., an outstanding scientific opportunity remains to complete "must-do" measurements in p+p and p+A physics at RHIC in the years preceding the EIC. It will be discussed how the new measurements will be essential for the quest to go beyond our current, one-dimensional picture of parton densities by correlating, for instance, the information on the contribution of a parton to the spin of the nucleon with its transverse momentum and spatial position. If one extends the scope from a nucleon to nuclei, questions about saturation, the partonic structure of nuclei and the propagation, attenuation and hadronization of colored quarks and gluons can be studied. The relevant measurements will be described together with improved detector capabilities at forward rapidities at both STAR and sPHENIX.
Speaker: Dr Elke-Caroline Aschenauer (BNL)
• 196
A Second Generation of Jefferson Lab 12-GeV Experiments - Towards Precision Spatial and Momentum Imaging of Hadrons
This talk will concentrate on the plans towards equipment and science utilizing the 12-GeV Upgrade at Jefferson Lab beyond the first three years of planned operations. Experiments are geared towards precision spatial and momentum imaging of hadrons utilizing specialized detector and/or target systems. For example, the Neutral-Particle Spectrometer in Hall C is presently under construction, and plans also exist for enhancements of equipment in Halls A and B towards detailed 3D imaging in the valence quark region.
Speaker: Rolf Ent (Jefferson Lab)
• 197
TMD Physics at 12-GeV Jefferson Lab with SoLID
(for the SoLID Collaboration) The Solenoidal Large Intensity Device (SoLID) has been proposed in Hall A at Jefferson Lab, which will fully utilize the great physics potential of the 12-GeV energy upgrade by combining high luminosities and large acceptance. Three of five highly-rated approved experiments are the semi-inclusive deep inelastic scatterings (SIDIS) of 11 GeV and 8.8 GeV electron beams on transversely and longitudinally polarized 3He targets and a transversely polarized proton target with detection of charged pions and electrons in coincidence to study the transverse momentum dependent parton distributions (TMDs). The SoLID SIDIS experiment will provide 4-d (x, z, Q2, PT) mappings of Sivers, Collins, pretzelostiy and worm-gear asymmetries in the valence quark region with high precision. In this talk, we will present the expected physics results from SoLID SIDIS measurements on TMD extractions, transversity distributions, and the tensor charge of u and d quarks. The constraint on quark electric dipole moments (EDMs) with the tensor charge measurement and neutron EDM experiments will also be discussed. This work is supported in part by the US Department of Energy under contract numbers DE-FG02-03ER41231 and by the Duke Kunshan University.
Speaker: Dr Tianbo Liu (Duke University and DKU)
• 4:02 PM
Coffee break
• WG1 Structure Functions and Parton Densities Auditorium

### Auditorium

#### DESY Hamburg

Conveners: Dr Katarzyna Wichmann (DESY), Prof. Robert Thorne (University College London), Prof. Ronan McNulty (University College Dublin)
• 198
Resummations in PDF fits
I will discuss the inclusion in PDF fits of two resummations in QCD: threshold (large x) and high-energy (small x). I will present published results for threshold resummation on a global NNPDF, and implication for phenomenology (as well as future plans). I will then show preliminary results on the effect of resumming small-x logarithms in PDF fits, again in the context of the NNPDF methodology.
Speaker: Dr Marco Bonvini (University of Oxford)
• 199
Recent developments in APFEL
APFEL is a numerical code specialized for PDF fits that provides a fast and accurate solution of the DGLAP equations up to NNLO in QCD and LO in QED. In addition to PDF evolution, APFEL also provides a module that computes deep-inelastic scattering cross sections in several mass schemes up to NNLO in QCD. In this contribution I will present the most recent developments carried out in the APFEL framework. They include: the implementation of the intrinsic charm contributions to the FONLL structure functions, the computation of the polarized evolution up to NNLO in QCD, the small-x resummed evolution up to NLL, the implementation of the single-inclusive cross sections needed for the determination of fragmentation functions (FFs). APFEL is currently used by the NNPDF collaboration and is interfaced to the xFitter public code and thus all these developments are or will be used to improve the determination of PDFs and FFs.
Speaker: Dr Valerio Bertone (University of Oxford)
• 200
Charm in Deep-Inelastic Scattering
I will discuss the extension of the FONLL variable flavour number scheme to account for a possible intrinsic component of the charm PDF. I will present the results of a PDF fit which includes a fitted charm PDF in the NNPDF framework, and discuss phenomenological implications.
Speaker: Mr Luca Rottoli (University of Oxford)
• 201
xFitter project
An accurate knowledge of the Parton Distribution Functions (PDF) plays a critical role for the precision tests of the Standard Model (SM) and impact substantially the theory predictions of Beyond SM high mass production. We present the xFitter project (former HERAFitter) which provides a unique open-source software framework for the determination of the proton's PDFs and for the interpretation of the physics analyses in the context of Quantum Chromodynamics. We highlight the new xFitter software release which includes many new features and additions, e.g. the possibility of the inclusion of photon PDF, updated variable and fixed-flavour schemes for heavy quarks, interface to the APFEL library and n-space evolution program MELA, updates to the latest theory calculations, fast grid tools and many more. We will also report the highlighted results based on the xFitter functionalities, as well as novel studies performed by xFitter.
Speaker: Mr Oleksandr Zenaiev (DESY)
• 202
The CT14 MC replicas
The Parton Distribution Functions(PDFs) are the non-perturbative input of the theoretical calculation of physical observable in a hadron collider. In the era of precision measurement, the uncertainty estimation of the PDFs is sensitive to the searching of new physics. In this talk, the CT14 Monte Carlo replica and its comparison with the CT14 Hessian sets would be presented.
Speaker: Dr Tie-Jiun Hou (Southern Methodist University)
• 203
On the asymptotic behaviour of parton distribution functions at small and large x
The behaviour of parton distribution functions (PDFs) at sufficiently small and large values of momentum fractions is expected to be governed by a power law, as a result of Regge theory and spectator counting rules respectively. I investigate in which regions of momentum fraction and energy such an asymptotic behaviour emerges, based on recent determinations of PDFs from a global analysis of experimental data. I discuss how these compare with theoretical expectations provided by perturbative and non-perturbative quantum chromodynamics (QCD) and models of nucleon structure, I examine how much the latter can be discriminated by the data, and I comment on how these are related to our first-principle understanding of QCD.
Speaker: Dr Emanuele Roberto Nocera (Rudolf Peierls Centre for Theoretical Physics University of Oxford)
• WG2 QCD and Hadronic Final States SR1 (DESY, Hamburg)

### SR1

#### DESY, Hamburg

Conveners: Frank Tackmann (DESY), Dr Shima Shimizu (Kobe University), Dr Simon Plätzer (DESY Theory Group)
• 204
Parton shower development
Review of recent development in parton showers.
Speaker: Dr Zoltan Nagy (DESY Theory Group)
• 205
New Insights into Coloumb Gluons
Coloumb gluons and ordering variable.
Speaker: Dr Rene Angeles Martinez (University of Manchester)
• 206
Measurements of dijet azimuthal decorrelation at 8 TeV from CMS
A measurement of the decorrelation of azimuthal angles between the two jets with the largest transverse momenta is presented for seven regions of leading jet transverse momentum up to 2.2 TeV. The results are compared to fixed-order predictions of perturbative quantum chromodynamics (QCD), and to simulations using Monte Carlo event generators that include parton showers, hadronization, and multiparton interactions. We discuss also experimental effects like jet-energy-corrections.
Speaker: Panos Kokkas (University of Ioannina in Ioannina, Greece)
• 207
Measurement of jet properties with the ATLAS detector
The average charge and the multiplicity of charged hadrons within a jet provide new insights into the modeling of strong interactions. The jet charge can also be used to tag hadronically decaying gauge bosons and the number of charged particles within a jet provides a powerful means to distinguish gluon-initiated from quark-initiated jets. The ATLAS collaboration has used a selection of di-jet events in 20.3 /fb of data collected at a center-of-mass energy of 8TeV to measure the average charged-particle multiplicity and the transverse-momentum weighted average charge of the hadrons within the jets, separately for the more central and the more forward jet and as a function of the jet transverse momentum. The results have been compared with calculations at NLO in pQCD and with predictions of MC generators interfaced with various parton distribution functions and underlying-event tunes.
Speaker: Pierre-Hugues Beauchemin (Tufts University)
• 208
Parton-shower effects in vector-boson-fusion processes
Production of electroweak bosons via vector-boson fusion (VBF) is one of the main process classes to study during the run-2 phase of the LHC. Its double-DIS-like structure gives rise to the characteristic signature of two tagging jets in the forward regions of the detectors, and distinguishes it from QCD-induced processes, which exhibit much more central jet activity. VBF processes allow to study the triple and quartic gauge couplings and test them for new-physics effects. In this talk, we investigate the effects of combining NLO QCD results with parton-shower effects using the latest versions of VBFNLO 3 and Herwig 7. A consistent treatment of renormalization and factorization scale variations in the hard process and the parton shower allows to assign more reliable theory uncertainty predictions to key distributions like the central rapidity gap. Additionally, we compare the effect of parton-shower and new-physics effects on distributions and study how to distinguish the two.
Speaker: Michael Rauch (ITP, KIT)
• WG3 Electroweak Physics and Beyond the Standard Model SR4b

### SR4b

#### DESY Hamburg

Conveners: Prof. Kevin Black (Boston University), Prof. Sanjay Padhi (Brown University), Prof. Shufang Su (University of Arizona)
• 209
Interpreting the 750 GeV diphoton signal as technipion
We discuss a scenario in which the enhancement in the diphoton final state at $M_{\gamma \gamma}$ = 750 GeV, recently observed by the ATLAS and CMS collaborations, is a technipion. We consider two different detailed minimal scenarios. In a first one (vector-like technicolor model) we assume that the vector-boson fusion is a dominant production mechanism. In a second one (one family walking technicolor model) the technipion is produced dominantly by the gluon-gluon fusion. We adjust parameters of the model (coupling constant) to the size of the signal at $\sqrt{s}$ = 13 TeV and discuss the size of the signal at lower energies (LHC, Tevatron) for $\gamma \gamma$ and jet-jet final states, where it was not observed and check consistency with the existing data. The signal is compared with the background diphoton contributions. As background contributions we include $q \bar q$ annihilation, gluon-gluon fusion via quark boxes, as well as photon-photon fusion via lepton, quark and $W$-bosons boxes. In the latter case (background) as well as for the technipion production (signal) we include elastic-elastic, elastic-inelastic, inelastic-elastic and inelastic-inelastic photon-photon processes, where inelastic'' means associated e.m. dissociation of a proton. In both cases we observe the dominance of inelastic-inelastic processes. We consider also an alternative partonic approach with 2 $\to$ 3 subprocess (with off-shell photons) and compare it to the approach with on shell photons. We predict the signal cross section for purely exclusive $p p \to p p \gamma \gamma$ procesess at $\sqrt{s}$ = 13 TeV to be about 0.5 fb. Such a cross section would be measurable with integrated luminosity about 20 fb$^{-1}$. In all considered cases (other experiments) the signal is below the background or/and below the threshold set by statistics although some tension can be seen. The presentation will be based on our upcoming paper [1]. [1] P. Lebiedowicz, M. {\L}uszczak, R. Pasechnik and A. Szczurek, a paper in preparation.
Speaker: Prof. Antoni Szczurek (Institute of Nuclear Physics PAN, Krakow and Rzeszow University, Rzeszow)
• 210
The Higgs singlet extension at LHC Run 2
I discuss the current status of theoretical and experimental constraints on the real Higgs singlet extension of the Standard Model. For the second neutral (non-standard) Higgs boson the full mass range from 1 GeV to 1 TeV accessible at past and current collider experiments is considered. I present benchmark scenarios for searches for an additional Higgs state in the real Higgs singlet extension of the Standard Model in Run 2 of the LHC.I will furthermore discuss electroweak corrections to the H to hh partial decay width within this model.
Speaker: Dr Tania Robens (IKTP, TU Dresden)
• 211
Exploring Anomalous $HZ\gamma$ Couplings in $\gamma$-proton Collisions at the LHC
The anomalous $HZ\gamma$ couplings, which are dominated by the new physics effects, through the process $pp\rightarrow p\gamma p\rightarrow p H X$ at the LHC are studied. To this purpose, an effective Lagrangian, in a model independent approach, with dimension six operators is considered in this paper. New interaction terms regarding beyond the standard model physics include the Higgs particle anomalous vertices in both CP-even and CP-odd structures. A detailed numerical analysis is performed to scrutinize the accurate constraints on the effective $HZ\gamma$ couplings and to discus how far the corresponding bounds can be improved. This is achieved by testing all the possible Higgs decay channels and increasing the luminosity at three different forward detector acceptance regions. The numerical results propose that the Higgs photoproduction at the LHC, as a complementary channel, has a great potential of exploring the $HZ\gamma$ couplings.
Speaker: Dr Sara Taheri Monfared (IPM)
• 212
Boosting Higgs pair production in the $b\bar{b}b\bar{b}$ final state with multivariate techniques
The measurement of Higgs pair production will be a cornerstone of the LHC program in the coming years. Double Higgs production provides a crucial window upon the mechanism of electroweak symmetry breaking and has a unique sensitivity to the Higgs trilinear coupling. We study the feasibility of a measurement of Higgs pair production in the b ̄bb ̄b final state at the LHC. Our analysis is based on a combination of traditional cut- based methods with state-of-the-art multivariate techniques. We account for all relevant backgrounds, including the contributions from light and charm jet mis-identification, which are ultimately comparable in size to the irreducible 4b QCD background. We demonstrate the robustness of our analysis strategy in a high pileup environment. For an integrated luminosity of L = 3 ab−1, a signal significance of S/√B ≃ 3 is obtained, indicating that the b ̄bb ̄b final state alone could allow for the observation of double Higgs production at the High Luminosity LHC.
Speaker: Dr Nathan Hartland (Oxford)
• 213
The EW Sudakov approximation in SHERPA
Monte Carlo event generators are currently very important tools for the comparison between theory and experiment at particle colliders. Today, these tools typically reach NLO precision in QCD for the fixed-order matrix element. In order to improve this precision, Monte Carlo event generators must compute to NLO in EW as well as to NNLO in QCD. The inclusion of a full NLO EW calculation is computationally expensive and is also non-trivial to include on top of a NLO QCD calculation. It is, however, possible to include the most dominant terms of the NLO EW calculation in the high-energy limit without the overhead of performing the complete calculation. These dominant terms are the large logarithms, called 'EW Sudakov logarithms', which result from the soft-collinear limit of weak boson exchange. Unlike in QCD and QED, the mass of the weak bosons introduces a natural cut-off, which leaves these logarithms large and finite in the high-energy regime. This talk presents the implementation of these logarithms as a K-factor to the underlying Born process within the SHERPA Monte Carlo event generator.
Speaker: Dr Jennifer Thompson (II. Physikalisches Institut, Georg-August-Universitaet Goettingen)
• WG4/WG5 joint session (HF+diffraction) SR2

### SR2

#### DESY Hamburg

Conveners: Dr Alessia Bruni (INFN Bologna), Leszek Motyka (Jagiellonian University), Mr Martijn Mulders (CERN), Maximilian Stahlhofen (DESY), Mr Mikhaylo Lisovyi (PI Heidelberg University), Dr Rainer Schicker (Phys. Inst., Heidelberg)
• 214
Diffractive production of heavy mesons at the LHC within k_t -factorization approach
We discuss diffractive production of open charm and bottom mesons at the LHC [1]. The differential cross sections for single- and central-diffractive mechanisms for c ̄c and b ̄b pair production are calculated in the framework of the Ingelman-Schlein model corrected for absorption effects. In this approach one assumes that the pomeron has a well defined partonic structure, and that the hard process takes place in a pomeron-proton or proton-pomeron (single diffraction) or pomeron-pomeron (central diffraction) processes. Here, leading-order gluon-gluon fusion and quark-antiquark anihilation partonic subprocesses are taken into consideration. Both pomeron flux factors as well as parton distributions in the pomeron are taken from the H1 Collaboration analysis of diffractive structure function and diffractive dijets at HERA. The extra corrections from subleading reggeon exchanges are explicitly calculated and are also taken into consideration. Predictions for single- and central-diffractive production in the case of inclusive D and B mesons, as well as D ̄D correlations are presented, including detector acceptance of the ATLAS, CMS and LHCb Collaborations. The experimental aspects of possible standard and dedicated measurements are carefully discussed. For the first time, the differential cross sections for the diffractive c ̄c pair production are calculated in the framework of the k_t -factorization approach, i.e. effectively including higher-order corrections. The unintegrated (transverse momentum dependent) diffractive parton distributions in proton are calculated with the help of the Kimber-Martin-Ryskin prescription where collinear diffractive PDFs are used as input. The latter are obtained by means of the Ingelman-Schlein model. Several quark-level differential cross sections are shown, including one-dimensional distribution and two-dimensional correlation distributions (e.g. φ_ {c ̄c} - azimuthal angle correlations or pair transverse momentum p_t distributions. The hadronization of charm quarks is taken into account by means of fragmentation function technique. Predictions for single-diffractive production of D^0 meson including detector acceptance of the ATLAS experiment are presented. Crucial aspects of possible standard and dedicated measurements within the ATLAS detector are also discussed. [1] M. Luszczak, R. Maciula and A. Szczurek, Single- and central-diffractive production of open charm and bottom mesons at the LHC: theoretical predictions and experimental capabilities, Phys. Rev. D 91 (2015), 054024. [2] M. Luszczak, R. Maciula, A. Szczurek and M. Trzebinski, Diffractive charm production at the LHC within k_t -factorization approach, a paper in preparation. E-mail: luszczak@ur.edu.pl
Speaker: Dr Marta Luszczak (University of Rzeszow)
• 215
Coherent photo-nuclear production of vector mesons at mid-rapidities in Pb-Pb collisions
ALICE has measured the coherent photo-nuclear production of $\rho^0$, J/$\psi$ and $\psi(2S)$ vector mesons at mid-rapidity in ultra-peripheral collisions of lead nuclei. These processes provide information on the gluon structure of the nuclear target at low Bjorken-$x$. The talk will cover the results from LHC Run1 data, as well as discuss the current status and prospects for analyses with LHC Run2 data.
Speaker: Prof. Guillermo Contreras (Czech Technical University)
• 216
Production of a forward J/Psi and a backward jet at the LHC
J/Psi mesons are copiously produced at the LHC. Inspired by the Mueller Navelet jet studies, we propose to consider the production of a forward J/Psi accompanied by a backward jet. We make a feasibility study for this process and we compute the leading order differential cross section for such events in the BFKL framework.
Speaker: Renaud Boussarie (CNRS, Univ. Paris-Sud, 91405 Orsay, France)
• 217
Photoproduction of $J/\psi$ and $Upsilon$ states in exclusive and proton-dissociative diffractive events
The amplitude for $\gamma p \to V p$, where $V$ is a $J/\psi$ or $\Upsilon$ ground state or excited vector meson, is calculated in a pQCD $k_{T}$-factorization approach. We use this amplitude to predict the cross section for exclusive photoproduction of $J/\psi, psi', \Upsilon$ mesons in proton-proton collisions. Calculations are performed for a variety of unintegrated gluon distributions, and we compare to LHCb data. Here we especially focus on the possibilty of constraining saturation effects. Compared to earlier calculations we include both Dirac and Pauli electromagnetic form factors. We discuss the role of the $Q\bar Q$ light-cone wave functions for differential distributions for ratios such as $\sigma(\psi')/\sigma(J/\psi)$. Absorption effects are always taken into account. We also discuss the related diffractive production in proton dissociative events. Here special emphasis is put on electromagnetic dissociation , which is calculable without additional free parameters. Besides being of interest in their own right, dissociative events constitute an important experimental background to exclusive production. We also comment on the role of dissociative photoproduction for other states, e.g. light vector mesons. The talk will be based on A. Cisek, W. Scha\"fer and A. Szczurek, JHEP 1504 (2015) 159 and ongoing work by the same authors.
Speaker: Dr Wolfgang Schafer (Institute of Nuclear Physics PAN)
• 218
D* Production in diffractive DIS at HERA
Measurements of open charm production are presented in diffractive deep inelastic scattering (5 < Q2 < 100 GeV2), based on HERA data recorded at √s = 319 GeV with an integrated luminosity of 281 pb-1. The event topology is given by ep → eXY, where the system X, containing at least one D(2010) meson, is separated from a leading low-mass proton dissociative system Y by a large rapidity gap. The D candidates are reconstructed fully in the D*+ → D0 π+ → (K- π+) π+ (+C.C.) decay channel. The measured differential cross sections are compared at the level of stable hadrons with next-to-leading order QCD predictions obtained in the massive scheme, where the charm quark is produced via the boson-gluon fusion, using diffractive parton densities previously obtained by H1 from fits of the inclusive diffractive cross sections.
Speaker: Karel Cerny (Charles University in Prague)
• WG6 Spin Physics SR4a

### SR4a

#### DESY Hamburg

Conveners: Dr Emanuele Roberto Nocera (Rudolf Peierls Centre for Theoretical Physics University of Oxford), Dr Erin Seder (CEA Saclay DSM/IRFU/SPhN/LSN), Dr Salvatore Fazio (Brookhaven National Laboratory), Dr Silvia Pisano (Laboratori Nazionali di Frascati - INFN)
• 219
Experimental overview of DVCS and Generalized Parton Distributions at Jefferson Lab
Generalized Parton Distributions (GPDs) are nowadays the object of an intense effort of research, in the perspective of understanding nucleon structure. They describe the correlations between the longitudinal momentum and the transverse spatial position of the partons inside the nucleon and they can give access to the contribution of the orbital momentum of the quarks to the nucleon spin. Deeply Virtual Compton scattering (DVCS), the electroproduction on the nucleon, at the quark level, of a real photon, is the process more directly interpretable in terms of GPDs of the nucleon. Depending on the target nucleon (proton or neutron) and on the DVCS observable extracted (cross sections, target- or beam-spin asymmetries,...), different sensitivity to the various GPDs for each quark flavor can be exploited. This talk will be focused on recent promising results, obtained at Jefferson Lab, on cross sections and asymmetries for DVCS, and their link to the Generalized Parton Distributions. These data have opened the way to a “tomographic” representation of the structure of the nucleon, allowing the extraction of transverse-space densities of the quarks at fixed longitudinal momentum. The extensive experimental program to measure GPDs at Jefferson Lab with the 12-GeV-upgraded electron accelerator and the complementary detectors that will be housed in three experimental Halls (A, B, C), will also be presented.
Speaker: Silvia Niccolai (IPN Orsay)
• 220
Exclusive Hard Processes with CLAS and Generalized Parton Distributions
An extensive experimental program with the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab has been under way to study the 3-dimensional structure of the nucleon through investigating Generalized Parton Distributions (GPDs) by measuring hard exclusive processes such as deeply virtual Compton scattering (DVCS) and deeply virtual meson production (DVMP). The GPDs provide a route to spatial tomography of the nucleon and have revolutionized how we characterize nucleon structure, by allowing a unified description of quark densities in spatial coordinates in relation to their momenta. Studies of the GPDs will be the focus of a sizable part of the program of the 12 GeV CEBAF upgrade and a driving force behind the construction of the Electron Ion Collider (EIC). In this contribution, we present recent results of the target spin and double spin asymmetries from deeply virtual Compton scattering (DVCS) and deeply virtual neutral pion production. Data were taken at Jefferson Lab using the CLAS detector and a longitudinally polarized 14 NH 3 target with a 6 GeV polarized electron beam. These results could provide new insights into the 3-dimensional nucleon structure.
Speaker: Kyungseon Joo (University of Connecticut, Storrs, CT 06269, USA)
• 221
The t-dependence of the pure DVCS cross-section at COMPASS
A major part of the COMPASS-II program will be dedicated to the investigation of generalized parton distributions (GPDs) and transverse momentum dependent parton distributions (TMDs), which aim for the most complete description of the partonic structure of the nucleon. GPDs are experimentally accessible via lepton-induced exclusive reactions, in particular the Deeply Virtual Compton Scattering (DVCS) and Deeply Virtual Meson Production (DVMP). At COMPASS, those processes are investigated using an high intensity muon beam of 160 GeV and a 2.5 m-long liquid hydrogen target. In order to optimize the selection of exclusive reactions at those energies, the target is surrounded by a new barrel-shaped time-of-flight system to detect the recoiling particles. COMPASS-II covers the up to now unexplored $x_{Bj}$ domain ranging from 0.01 to 0.15. The option to change simultaneously the charge and polarization of the muon beam allows to perform DVCS measurements on a proton target and to access the Compton form factor related to the dominant GPD $H$, and thus to provide new experimental constraints on the theoretical GPD models in the intermediate $x_{Bj}$ regime. From the sum of cross-sections measured with positive and negative beam polarity, the pure DVCS cross-section can be extracted. Pilot measurements for the COMPASS II program allow for an extraction of the $t$-dependence of the pure DVCS cross-section in a single $x_{Bj}$ bin. This provides first information on the nucleon transverse size in an up to now uncharted $x_{Bj}$ regime.
Speaker: Mr Philipp Jörg (University of Freiburg)
• 222
Exclusive meson production at HERMES
The HERMES experiment has extensively studied exclusive meson production in deep-inelastic scattering of the 27.6 GeV electron/positron beam of HERA by various gaseous targets internal to the storage ring. Recent results on exclusive omega production are presented: spin-density matrix elements using unpolarized and longitudinally polarized leptons and unpolarized hydrogen and deuterium targets, and azimuthal distributions for scattering from transversely polarized protons. In addition, an analysis of ratios of helicity-amplitudes for exclusive production of rho mesons from transversely polarized protons is presented.
Speaker: Sergey Manaenkov (B.P. Konstantinov Petersburg Nuclear Physics Institute - PNPI)
• WG7 Future Experiments SR3

### SR3

#### DESY Hamburg

Conveners: Claire Gwenlan (Oxford), Dr Elke-Caroline Aschenauer (BNL), Dr Wally Melnitchouk (Jefferson Lab)
• 223
The Mu2e Experiment at Fermilab
The Mu2e Experiment at Fermilab will search for coherent, neutrinoless conversion of muons into electrons in the field of a nucleus with a sensitivity improvement of a factor of 10,000 over previous experiments. Such a charged lepton flavor-violating reaction probes new physics at a scale inaccessible with direct searches at either present or planned high energy colliders. The experiment both complements and extends the current search for muon decay to electron+gamma at MEG and searches for new physics at the LHC. We will present the physics motivation for Mu2e, the novel design of the muon beamline and the detector, and the current status of the experiment.
Speaker: Luca Morescalchi (Pisa)
• 224
SHiP: a new facility with a dedicated detector for studying tau neutrino properties and nucleon structure functions
SHIP is a new general purpose fixed target facility, whose Technical Proposal has been recently reviewed by the CERN SPS Committee, who recommended that the experiment proceeds further to a Comprehensive Design phase. In its initial phase, the 400GeV proton beam extracted from the SPS will be dumped on a heavy target with the aim of integrating $2\times 10^{20}$ pot in 5 years. A dedicated detector downstream the target will allow to probe a variety of models with light long-lived exotic particles and masses below a few GeV/c$^2$. Another dedicated detector will allow the study of neutrino cross-sections and angular distributions, and it will be the focus of the talk. $\nu_\tau$ deep inelastic scattering cross sections will be measured with a statistics 1000 times larger than currently available, with the extraction of the $F_4$ and $F_5$ structure functions, never measured so far and allow for new tests of lepton non-universality with sensitivity to BSM physics. Moreover, $\nu_\tau$'s will be distinguished from $\bar{\nu}_\tau$'s, thus providing the first observation of the $\bar{\nu}_\tau$. With $\nu_\mu$ scattering it will be possible to reduce by about 50\% the current uncertainty on the strange content of the nucleon in the range of the x variable between 0.05 and 0.3, complementary to LHC measurements. Eventually, it will be possible to improve existing limits on dark photons decaying into dark matter particles, with the elastic scattering of these ones on electrons. The detector will be based on several techniques developed for the OPERA experiment at LNGS.
Speaker: Ahnnarita Buonaura (University of Naples)
• 225
The Belle II Experiment
The Belle II experiment at the asymmetric $e^+e^-$ SuperKEKB collider is a major upgrade of the Belle experiment, which ran at the KEKB collider at the KEK laboratory in Japan. The design luminosity of SuperKEKB is $8\times 10^{35}$~cm$^{-2}$\,s$^{-1}$, which is about 40 times higher than that of KEKB. Commissioning of the main ring of SuperKEKB has started in February of this year and Belle~II is expected to accumulate an integrated luminosity of 50~ab$^{-1}$ well within the next decade. The experiment will focus on searches for new physics beyond the Standard Model via high precision measurements of heavy flavor and searches for rare signals. To reach these goals, the accelerator, detector, electronics, software, and computing systems are all being substantially upgraded. In this talk we present the status of the accelerator and of the different Belle II sub-detector upgrades.
Speaker: Dr Carlos Marinas (University of Bonn)
• 226
Belle II early physics program of bottomonia spectroscopy
The Belle II experiment at the SuperKEKB collider is a major upgrade of the KEK $B$ factory'' facility in Tsukuba, Japan. Phase 1 commissioning of the main ring of SuperKEKB has started in February 2016 and first physics data will be recorded in the second half of 2017 during the so-called Phase~2 commissioning, when the Belle II detector will be operated still without its vertex detector. In this talk we describe a possible physics program for this early data run at different center-of-mass energies, in particular at the $\Upsilon(3S)$ and $\Upsilon(6S)$ resonances, amongst other energy points.
Speaker: Dr Hua YE (DESY)
• 227
Belle II studies of missing energy decays and searches for dark photon production
The Belle II experiment at the SuperKEKB collider is a major upgrade of the KEK $B$ factory'' facility in Tsukuba, Japan. The machine is designed for an instantaneous luminosity of $8\times 10^{35}$~cm$^{-2}$\,s$^{-1}$, and the experiment is expected to accumulate a data sample of about 50 ab$^{-1}$ well within the next decade. With this amount of data, decays sensitive to physics beyond the Standard Model can be studied with unprecedented precision. One promising set of modes are physics processes with missing energy such as $B^+\to\tau^+\nu$, $B\to D^{(*)}\tau\nu$, and $B\to K^{(*)}\nu\bar\nu$ decays. The Belle II data also allows searches for candidates for the dark photon, the gauge mediator of a hypothetical dark sector, which has received much attention in the context of dark matter models.
Speaker: Dr Gianluca Inguglia (DESY)
• 7:00 PM
Bus transfer to conference dinner - Buses leave DESY between 19:00 and 19:10
• 8:00 PM
Conference Dinner
• 10:45 PM
Bus transfer to DESY, also continues to Bahrenfelder Trabrennbahn and Altona
• Thursday, April 14
• WG1 Structure Functions and Parton Densities Auditorium

### Auditorium

#### DESY Hamburg

Conveners: Dr Katarzyna Wichmann (DESY), Prof. Robert Thorne (University College London), Prof. Ronan McNulty (University College Dublin)
• 228
Quark and Gluon collinear and TMD parton distributions from HERA DIS data
We describe a new approach to solve the coupled quark and gluon evolution DGLAP evolution equations with a Monte Carlo method. We show that this method is equivalent to other methods. We apply this method to extract quark and gluon parton densities collinear and as transverse momentum dependent (TMD) distributions using the precision HERA DIS data. The Monte Carlo method for the solution of the evolution equation allows to estimate also large x threshold resummation effects.
Speaker: Aleksandra Lelek (DESY)
• 229
Saturation effect in TMD parton distributions obtained from HERA data
We apply a MC method to solve the evolution equations but use a gluon density from saturation models as input. The sea and valence quark disributions are obtained from fits to HERA precision data. We obtain TMD parton distributions (gluon and quarks) satisfying saturation conditions.
Speaker: Sara Taheri Monfared (IPM Istanbul)
• 230
Significance of gluon density for soft and hard processes at LHC
We study the role of the non-perturbative input to the transverse momentum dependent (TMD) gluon density in hard processes at the LHC. We derive the input TMD gluon distribution at a low scale $\mu_0^2 \sim 1$~GeV$^2$ from a fit of inclusive hadron spectra measured at low transverse momenta in $pp$ collisions at the LHC and demonstrate that the best description of these spectra for larger hadron transverse momenta can be achieved by matching the derived TMD gluon distribution with the exact solution of the Balitsky-Fadin-Kuraev-Lipatov (BFKL) equation obtained at low $x$ and small gluon transverse momenta outside the saturation region, see for example [1]. Then, we extend the input TMD gluon density to higher $\mu^2$ numerically using the Catani-Ciafoloni-Fiorani-Marchesini (CCFM) gluon evolution equation. Special attention is paid to phenomenological applications of the obtained TMD gluon density to some LHC processes, which are sensitive to the gluon content of a proton [2]. References. [1] Yu.V.Kovchegov, Phys. Rev. D61, 074018 (2000). [2] A.A.Grinyuk, A.V.Lipatov, G.I.Lykasov, N.P.Zotov, Phys. Rev. D93, 014035 (2016).
• 231
TMDlib and TMDplotter
We present the TMDlib project which contains a collection on transverse momentum dependent (TMD) parton distributions obtained in different frameworks. The TMDplotter is a a web based plotting tool for TMD parton distributions as well as for collinear parton distributions included in LHAPDF. TMDplotter has additional plotting features, such as parton luminosities for collinear and TMD parton distributions.
Speaker: Patrick Connor (DESY)
• WG3 Electroweak Physics and Beyond the Standard Model SR2

### SR2

#### DESY Hamburg

Conveners: Prof. Kevin Black (Boston University), Prof. Sanjay Padhi (Brown University), Prof. Shufang Su (University of Arizona)
• 232
New results from the NA48 experiment at CERN
Searches for lepton number violation and resonances in the K+- -->pi mu mu decays at the NA48/2 experiment The NA48/2 experiment at CERN collected a large sample of charged kaon decays into final states with multiple charged particles in 2003-2004. A new upper limit on the rate of the lepton number violating decay K+- --> pi-+ mu+- mu+- obtained from this sample is reported: 8.6 × 10^−{11} at 90% CL, which improves by more than an order of magnitude upon the previous measurements. Searches for two-body resonances in the K+- -->pi mu mu decays (including heavy neutral leptons and inflatons) in the accessible range of masses and lifetimes are also presented.
• 233
Recent results from the NA62 experiment at CERN
Neutral pion form factor measurement by the NA62 experiment The NA62 experiment at CERN collected a large sample of charged kaon decays with a highly efficient trigger for decays into electrons in 2007. The kaon beam represents a source of tagged neutral pion decays in vacuum. A measurement of the electromagnetic transition form factor slope of the neutral pion in the time-like region from ~1 million fully reconstructed pi0 Dalitz decay is presented. The limits on dark photon production in pi0 decays from the earlier kaon experiment at CERN, NA48/2, are also reported. ----------- Search for K+ to pi+ nu nu at NA62 K+->pi+nunu is one of the theoretically cleanest meson decay where to look for indirect effects of new physics complementary to LHC searches. The NA62 experiment at CERN SPS is designed to measure the branching ratio of this decay with 10% precision. NA62 took data in pilot runs in 2014 and 2015 reaching the final designed beam intensity. The quality of data acquired in view of the final measurement will be presented.
Speaker: Riccardo Aliberti (Mainz University)
• 234
Limits on the effective quark radius from inclusive ep scattering at HERA
The high precision HERA combined measurement of inclusive deep inelastic cross sections in neutral and charged current ep scattering, corresponding to a luminosity of about 1 fb-1, permits searches for new contributions to electron-quark scattering beyond the Standard Model up to TeV scales. A new approach to beyond the Standard Model analysis of the inclusive ep data is presented; simulataneous fits of parton distribution functions and contributions of "new physics" processes were performed. Results are presented considering a finite radius of quarks within the quark form-factor model. The resulting 95% C.L. upper limit on the effective quark radius is 0.43 x 10^-16 cm.
Speaker: Mr Oleksii Turkot (DESY)
• 235
Low-energy hadronic cross sections measurements at BABAR, and implication for the g-2 of the muon
The BABAR Collaboration has an intensive program  studying hadronic cross sections at low-energy e+e- annihilation, accessible via initial-state radiation. Our measurements allow significant improvements in the precision of the predicted value of the muon anomalous magnetic moment. These improvements are necessary for shedding light on the current ~3 sigma difference between the predicted and the experimental values. We have published results on a number of processes with two to six hadrons in the final state, and other final state are currently under investigation. We report here on the most recent results obtained by analysing the entire BABAR dataset.
Speaker: Denis Bernard (Ecole Polytechnique)
• WG4 Heavy Flavours SR4a

### SR4a

#### DESY Hamburg

Conveners: Mr Martijn Mulders (CERN), Maximilian Stahlhofen (DESY), Mr Mikhaylo Lisovyi (DESY/Hamburg Uni)
• 236
XYZ studies at BESIII
The BESIII Experiment collected large data samples for electron-positron collisions with center-of-mass above 4 GeV during 2013 and 2014. The analysis of these samples has resulted in a number of surprising discoveries, such as the discoveries of the electrically charged "Zc" structures, which, if resonant, cannot be accomodated in the traditional charm quark and anti-charm quark picture of charmonium. In this talk, we will review the current status of the analyses of the Zc structures, as well as a number of other interesting features in the new BESIII data samples.
Speaker: Dr Aiqiang Guo (IHEP and DESY)
• 237
Search for new exotic QCD states in proton-antiproton collisions at D0
We have used the full D0 dataset consisting of 10.4 fb-1 of proton-antiproton collision data to search for new exotic QCD states. We report on the results in specific channels.
Speaker: Mr Iain Bertram (Lancaster University)
• 238
X(3872) and its bottomonium counterpart at ATLAS
We present the measurement of the differential cross-section of the X(3872) state through its decays to J/psi pi pi final state . The cross-section was extracted for both prompt and non-prompt production. The existence of the X(3872) suggests the presence of its bottomonium counterpart X_b. Search for X_b with the ATLAS experiment in several final states, including Upsilon pi pi, is presented.
Speaker: Konstantinos Kordas (Aristotle Univ. of Thessaloniki)
• 239
J/psi and Upsilon production cross-sections at the ATLAS experiment
New measurements of prompt and non-prompt J/psi and of Upsilon production at a centre-of mass energy of 13 TeV are presented. Comparisons with theoretical predictions and precision measurements made at energies of 2.76, 7 and 8 TeV are discussed.
Speaker: Susan Cheatham (Lancaster)
• WG5 Small-x and Diffraction SR4b

### SR4b

#### DESY Hamburg

Conveners: Dr Alessia Bruni (INFN Bologna), Leszek Motyka (Jagiellonian University), Dr Rainer Schicker (Phys. Inst., Heidelberg)
• 240
Very forward energy distributions and jet production observed with CASTOR in CMS
The distribution of electromagnetic and hadronic energy in the very forward phase-space is measured with the CASTOR calorimeters located at a pseudorapidity of -5.2 to -6.6 in the very forward region of CMS. The energy distributions are very powerful benchmarks to study the performance of MPI in hadronic interactions models at 13TeV collision energy. Furthermore, also the jet-spectra for very low-pt jets in 7 and 13TeV pp collisions are obtained with CASTOR and compared to model predictions.
Speaker: Alex Beaudoin E Van Spilbeeck (Universiteit Antwerpen in Wilrijk, Belgium)
• 241
Forward energy density per pseudorapdidty and limiting fragmentation studied with CMS at 13TeV
The forward (HF) and very-forward (CASTOR) calorimeters of CMS are used to measure the density of energy per unit of pseudorapiditdy up to eta of 6.6 at 13TeV. The measurements are compared to model predictions. Furthermore, the corresponding data of transverse energy are compared to CMS measurements at lower center-of-mass energies, where all data are shifted by the beam rapidity. The result is a demonstration of limiting fragmentation in pp collisions over a wide range of energies.
Speaker: Igor Katkov (DESY)
• 242
Forward production of Drell-Yan dileptons at high energies and low dilepton invariant masses in a $k_t$-factorization approach: Do we see onset of saturation?
We discuss Drell-Yan production of dileptons at high energies in forward rapidity region in a hybrid high-energy approach which uses unintegrated gluon distributions in one proton and collinear quark/antiquark distributions in the second proton. Corresponding momentum-space formula for the differential cross sections in high-energy approximation has been derived and will be presented. The relation to the commonly used dipole approach is discussed. We conclude and illustrate that some results of the dipole approaches are too approximate, as far as kinemtics is considered, and in fact cannot be used when comparing with real experimental data. We find that the dipole formula is valid only in very forward/backward rapidity regions ($|y| >$ 5) that cannot be studied experimentally in the moment. We performed calculations of some differential cross sections for low-mass dilepton production by the LHCb and ATLAS collaborations. In distinction to most dipole approaches, we include all the four Drell-Yan structure functions, although the impact of interference structure functions is rather small for the relevant experimental cuts. We find that both side contributions ($g q/\bar q$ and $q/\bar q g$) have to be included even for the LHCb rapidity coverage which is in contradiction with what is usually done in the dipole approach. We present results for different unintegrated gluon distributions from the literature (some of them include saturation effects). We see no clear hints of saturation even at small $M_{ll}$ when comparing with the LHCb data. The presentation will be based on our upcoming paper [1]. [1] W. Sch\"afer and A. Szczurek, a paper in preparation, to appear 02/16.
Speakers: Prof. Antoni Szczurek (Institute of Nuclear Physics PAN, Krakow and Rzeszow University, Rzeszow), Wolfgang Schafer (Institute of Nuclear Physics PAN, Krakow)
• 243
We discuss single inclusive hadron production from a high energy quark scattering off a strong target color field in the Color Glass Condensate formalism. Recent calculations of this process at the next-to-leading order accuracy have led to negative cross sections at large transverse momenta. We identify the origin of this problem in an oversubtraction of the rapidity divergence into the Balitsky-Kovchegov evolution equation for the target. We propose a new way to implement the kinematical restriction on the emitted gluons to overcome this difficulty.
Speaker: Dr Bertrand Ducloue (University of Jyvaskyla)
• WG7 Future Experiments SR3

### SR3

#### DESY Hamburg

Conveners: Claire Gwenlan (Oxford), Dr Elke-Caroline Aschenauer (BNL), Dr Wally Melnitchouk (Jefferson Lab)
• 244
The ZEUS data preservation project
The ZEUS data preservation (ZEUS DP) project assures continued access to the data and documentation related to the experiment. It aims to provide the ability to continue the generation of valuable scientific results from these data in the future. This talk presents analysis opportunities within the ZEUS DP project and its benefits for the physics community. The implications of the preserved data are discussed in the context of current data analyses, verification of contemporary and future theoretical models and the planning of future experiments and analyses. The detailed documentation on the data preservation effort can serve as an example for the data preservation efforts in current and future experiments.
Speaker: Dr Andrii Verbytskyi (Max-Planck Institut für Physik)
• 245
The ATLAS Tile Calorimeter, its performance with 13 TeV proton-proton collisions, and its upgrades for the high luminosity LHC
The Tile Calorimeter (TileCal) is the central hadronic calorimeter of the ATLAS experiment at the LHC. Jointly with the other calorimeters it is designed for reconstruction of hadrons, jets, tau-particles and missing transverse energy. It also assists in the muon identification. A summary of the upgrades and performance results for TileCal using pp collisions from the initial LHC Run II at 13 TeV will be presented. For the high luminosity era a major upgrade of the TileCal electronics is planned, and the ongoing developments for on- and off-detector systems, together with expected performance characteristics and recent beam tests of prototypes, will be described.
Speaker: Tomas Davidek (Charles University, Prague)
• 246
High-luminosity LHC prospects with the upgraded ATLAS detector
Run-I at the LHC was very successful with the discovery of a new boson with properties compatible with those of the Higgs boson predicted by Standard Model. Precise measurements of the boson properties, and the discovery of physics beyond the Standard Model, are primary goals of the just restarted LHC running at 13 TeV collision energy and all future running at the LHC. The physics prospects with a pp centre-of-mass energy of 14 TeV are presented for 300 and 3000 fb-1 at the high-luminosity LHC. The ultimate precision attainable on measurements of the couplings of the 125 GeV boson to elementary fermions and bosons is discussed, as well as perspectives on the searches for partners associated with it. Supersymmetry is one of the best motivated extensions of the Standard Model. The current searches at the LHC have yielded sensitivity to TeV scale gluinos and 1st and 2nd generation squarks, as well as to 3rd generation squarks and electro-weakinos in the hundreds of GeV mass range. Benchmark studies are presented to show how the sensitivity improves at the future LHC runs. A considerable fraction of the parameter space for a wide variety of other BSM models has been probed with the 8 TeV data and initial 13 TeV data. The prospects of searches for new heavy bosons and dark matter candidates at 14 TeV are explored as well as the sensitivity of searches for anomalous top decays and di-boson production. For all these studies, a parameterised simulation of the upgraded ATLAS detector is used, taking into account the expected pileup conditions.
Speaker: Magdalena Slawinska (Nikhef National institute for subatomic physics)
• 247
The PANDA Experiment at FAIR
The PANDA experiment in preparation to be setup at FAIR (Facility for Antiproton and Ion Research) in Darmstadt, Germany will cover many important aspects of hadron physics with cooled anti-proton beams of unprecedented intensity and precision in the momentum range between 1.5 and 15 GeV/c. The versatile detector is designed to address a rich physics program. This includes spectroscopy of QCD bound states ranging from charmonium to states composed of light quarks only, which comprises studies of the recently and yet not understood X, Y, and Z states and searches for other exotics. Production of hyperons will shed further light on the strong interaction in the intermediate region between the perturbative and non-perturbative regime. Time-like nuclear form factors and properties of hadrons in medium will be accessible and round up the experimental program. In this talk aspects of the PANDA physics program will be highlighted. Major components of the detector are under construction. The current status of the experiment will be presented.
Speaker: Marc Pelizaeus (Ruhr-University Bochum)
• WG2 QCD and Hadronic Final States SR1

### SR1

#### DESY Hamburg

Conveners: Frank Tackmann (DESY), Dr Shima Shimizu (Kobe University), Dr Simon Plätzer (DESY Theory Group)
• 248
Measurement of the underlying event at 13TeV with the CMS experiment
The measurements of the underlying events (UE) in the event topology of leading jet and leading track are presented. UE activities are quantified in term of particle and energy density. The UE observables are calculated in the transverse region with respect to the direction highest pT jet/track. These UE observables are measured as a as function of the pT of the leading track and jet.
Speaker: Prof. Ada Solano (Torino University and INFN)
• 249
Measurements of the underlying-event properties with the ATLAS detector
A correct modelling of the underlying event in proton-proton collisions is important for the proper simulation of kinematic distributions of high-energy collisions. The ATLAS collaboration extended previous studies at 7 TeV with a leading track or jet or Z boson by a new study of Drell-Yan events in 1.1 /fb of data collected at a center-of-mass energy of 7TeV. In this new study the distributions of several topological event-shape variables based on charged particles are measured, both integrated and differential in the transverse momentum of the Drell-Yan lepton pair. These measurements are sensitive to the underlying-event as well as the onset of hard emissions. The results have been compared with the predictions of several state-of-the-art MC generators. The collaboration has also performed a first study of the number and transverse-momentum sum of charged particles as a function of pseudorapidity and azimuthal angle in a special data set taken with low beam currents at a center-of-mass energy of 13TeV. The results are compared to predictions of several MC generators.
Speaker: David Anthony Milstead (Stockholm University)
• 250
Cancellation of Glauber gluon exchange in the double Drell-Yan process
An essential part of any factorisation proof is the demonstration that the exchange of Glauber gluons cancels for the considered observable. In this talk I will show that this can be done for the double Drell-Yan process (the double parton scattering process in which a pair of electroweak gauge bosons is produced), both for the integrated cross section and for the cross section differential in the boson transverse momenta.
Speaker: Dr Jonathan Gaunt (Nikhef and VU)
• 10:32 AM
Coffee break
• WG1 Structure Functions and Parton Densities Auditorium

### Auditorium

#### DESY Hamburg

Conveners: Dr Katarzyna Wichmann (DESY), Prof. Robert Thorne (University College London), Prof. Ronan McNulty (University College Dublin)
• 251
The atmospheric prompt neutrino flux revisited
I will present a state-of-the-art prediction for the prompt atmospheric neutrino flux in the framework of perturbative QCD. The calculation was performed using a gluon PDF constrained at small-x by the inclusion of charm production measurements from the LHCb experiment at 7 TeV, and recently validated with the corresponding 13 TeV data [arXiv:1511.06346, arXiv:1506.08025]
Speaker: Mr Luca Rottoli (University of Oxford)
• 252
From deep-inelastic structure functions to two-photon dilepton production in proton-proton collisions
We investigate different methods to incorporate the effect of photons in hard processes. We compare two different approaches used for calculating cross sections for two-photon $p p \to l^+ l^- X$ process. In one of the approaches photon is treated as a collinear parton in the proton. In the second approach recently proposed a $k_t$-factorization method is used. We discuss how results of the collinear parton model depend on the initial condition for the QCD evolution and discuss an approximate treatment where photon is excluded from the combined QCD-QED evolution. We demonstrate that it is not necessary to put photon into the evolution equation as often done recently but it is sufficient to use a simplified approach in which photon couples to quarks and antiquarks which by themselves undergo DGLAP evolution equations. Our $k_t$-factorization results (inelastic photon fluxes in the nucleon) depend on deep-inelastic structure function. We discuss sensitivity of the results to the choice of structure function parametrization and experimental cuts in the $k_t$-factorization approach. We find that results are sensitive to the region of $x$ and $Q^2$ where pQCD DGLAP evolution does not apply. We compare results of our calculations with recent experimental data for dilepton production and find that in most cases the contribution of the photon-photon mechanism is rather small. We discuss how to enhance the photon-photon contribution. We also compare our results to those of recent measurements of exclusive and semi-exclusive $e^+ e^-$ pair production with new experimental data obtained by the CMS collaboration. The presentation will be based on our recent papers [1], [2]. [1] G.~G.~da Silveira, L.~Forthomme, K.~Piotrzkowski, W.~Sch\"afer and A.~Szczurek, Central $\mu^{+} \, \mu^{−}$ production via photon-photon fusion in proton-proton collisions with proton dissociation,'' JHEP {\bf 1502}, 159 (2015) [arXiv:1409.1541 [hep-ph]]. [2] M. {\L}uszczak, W. Sch\"afer and A. Szczurek, "Two-photon dilepton production in proton-proton collisions: two alternative approaches," [arXiv:1510.00294 [ hep-ph]].
Speaker: Prof. Antoni Szczurek (Institute of Nuclear Physics, Polish Academy of Sciences)
• 253
A Lattice Calculation of Parton Distributions
Although Parton Distribution Functions are the fundamental objects describing the inner structure of hadrons, there exists so far no computation of them from first principles. The most promising candidate for such calculation, lattice QCD, performed successful computations for the masses, charges and form factors but not of the distributions themselves. The reason for this is that quark distributions are given by light-cone correlations and simulations of them are difficult to be done on an Euclidian lattice. However, a recent proposal allows the light-cone distributions to be extracted from purely spatial correlations, being thus accessible by lattice methods. We present here the latest results of our effort to perform an ab-initio lattice calculation of the nonsinglet combinations for $u(x) – d(x)$, $\Delta u(x) - \Delta d(x)$, and $\delta u(x) - \delta d(x)$, on a $32^3 \times 64$ lattice. We also discuss the challenges of the present calculations, possible extensions and the status of the renormalization program for these objects.
Speaker: Dr Fernanda Steffens (DESY - Zeuthen)
• 254
Exclusive J/ψ and Υ photoproduction and the low x gluon
We discuss the potential to constrain the small-x PDFs using the exclusive production of heavy vector mesons. The calculation of J/psi and Upsilon photoproduction at NLO in collinear factorisation is described. The different behaviour of the NLO corrections for J/psi and Upsilon is highlighted and we outline what might be expected from the inclusion of these processes in a PDF fit.
Speaker: Dr Stephen Jones (MPI, Munich)
• 255
Impact of Light-cone models for intrinsic charm on production of γ+c- jet differential cross section at LHC and Tevatron
Charm quark distribution function play an important role in study of many presses. In the standard global analysis of parton distribution functions, charm quark distribution arises perturbatively by gluon splitting. Nonetheless, existence of a non-perturbative intrinsic charm quark component in the nucleon is predicted by QCD. We present some phenomenological light cone models for non-perturbative intrinsic charm quark component. We investigate the impact of the charm quark distribution on production of γ + c-jet differential cross section in pp and pp(bar) collisions at LHC and Tevatron.
Speaker: Saeedeh Rostami (Semnan University, Iran)
• 256
Stability structure of the GLR equation
We investigate the stability of the saturation regime of the Gribov-Levin-Ryskin equation against azimuthal perturbations, and argue that the appearance of unstable modes could lead to the "spontaneus symmetry breaking" of azimuthal symmetry in high energy pp and AA collisions. We discuss the phenomenology of this hypothesis in light of the "harmonic flow" observable seen in heavy ion collisions.
Speaker: Mr Guillermo Gambini (IFGW-Unicamp)
• WG2 QCD and Hadronic Final States SR1 (DESY, Hamburg)

### SR1

#### DESY, Hamburg

Conveners: Frank Tackmann (DESY), Dr Shima Shimizu (Kobe University), Dr Simon Plätzer (DESY Theory Group)
• 257
Double parton scattering results obtained by CMS
The double parton scattering (DPS) in proton-proton collisions at a center-of-mass energy of 8 TeV has been investigated using various final states. Multi-Jet, including b-jets, photon-jets as well as same-sign W bosons with each W boson decaying into muon and associated neutrino. The observables most sensitive to double parton scattering are defined and studied. A multivariate analysis is developed in order to enhance the DPS sensitivity. A limit on the DPS yield has been evaluated.
Speaker: Gilvan Augusto Alves (Centro Brasileiro de Pesquisas Fisicas in Rio de Janeiro, Brazil)
• 258
Double Parton Scattering effects in 4 jet production at the LHC
We study both the single and double parton scattering contributions to 4 jet production in kt-factorization using off-shell matrix elements and KMR PDFs. We compare them to the collinear case and find that the expected relevance of the Double Parton Scattering contribution is tamed in the kt-factorization framework: in particular, kinematic cuts should be chosen carefully as we thoroughly discuss.
Speaker: Dr Mirko Serino (Institute of Nuclear Physics, PAN, Cracow)
• 259
Searching for optimal conditions for exploration of double-parton scattering in four-jet production at the LHC
Double-parton scattering (DPS) effects were discussed recently for different reactions. So far no clear and spectacular effect was observed for jet production where single-parton scattering (SPS) contributions dominate. We discuss four-jet production at the LHC. We calculate cross section for both single-parton scattering (SPS) using the ALPGEN code and for double-parton scattering (DPS) in collinear approach [1] as well as in $k_t$-factorization approach [2]. Our results are compared with experimental data obtained recently by the CMS Collaboration [3]. We show that the ALPGEN code relatively well describes distributions in rapidity of each of the four jets ordered by their transverse momenta. The SPS mechanism does not explain the distributions at large rapidity for the leading, second, third and fourth jet. The DPS mechanism improves the agreement with the experimental data in this corner of the phase space. We try to find better conditions where the relative DPS contribution is enhanced. This would open a possibility to explore the DPS effects experimentally. The total cross sections for the DPS mechanism obtained witin the $k_t$-factorization approach are slightly smaller than in the case of the collinear approach. Application of the $k_t$-factorization framework extends our former analysis of different correlation observables that may be useful for further experimental identification of the DPS effects in four-jet sample \cite{MS2016}. Results obtained in the two approaches are compared and appearing differences are discussed. [1] R. Maciula and A. Szczurek, Searching for and exploring double-parton scattering effects in four-jet production at the LHC, Phys. Lett. B 749 (2015) 57-62. [2] R. Maciula et al., a paper in preparation. [3] S. Chatrchyan et al. [CMS Collaboration], Measurement of four-jet production in proton-proton collisions at $\sqrt{s}=7$ TeV, Phys. Rev. D 89, 092010 (2014).
Speaker: Dr Rafal Maciula (the Institute of Nuclear Physics PAS)
• 260
Associated production of electroweak bosons and heavy mesons at LHCb and prospects to observe double parton interactions
The production of weak gauge bosons in association with heavy flavored mesons at the LHCb conditions is considered, and a detailed study of the different contributing processes is presented including single and double parton scattering mechanisms. We conclude finally, that double parton scattering dominates the production of same-sign WD states, as well as the production of W- bosons associated with B-mesons. The latter processes can thus be regarded as new useful DPS indicators.
Speaker: Dr Maxim Malyshev (SINP MSU)
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