13th Annual Meeting of the Helmholtz Alliance "Physics at the Terascale"
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Europe/Berlin
DESY Hamburg
DESY Hamburg
Description
Welcome to the 13th Annual Helmholtz Alliance Workshop on "Physics at the Terascale"! As in the past 12 years, the workshop will offer a rich programme of stimulating plenary talks and parallel sessions full of intense discussion on topics connected to the LHC, linear colliders, and Belle. The following parallel sessions will be held:
- Higgs physics
- Searches
- Top physics
- B physics
- Standard Model physics
- Computing and Machine Learning
Support
Participants
154
View full list
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14:00
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18:00
Linear Collider ForumConveners: Dr Frank Simon (Max-Planck-Institute for Physics), Gudrid Moortgat-Pick (University of Hamburg / DESY), Prof. Ivor Fleck (University of Siegen), Sabine Riemann (DESY)
- 14:00
- 14:30
- 15:00
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15:30
Coffee break 30m
- 16:00
- 16:30
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18:00
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- 09:00 → 11:00
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11:00
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11:30
Coffee break 30m
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11:30
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13:10
Flavor physics SR 4b
SR 4b
DESY Hamburg
Conveners: Dr Christoph Langenbruch (RWTH Aachen), Mr Danny van Dyk (Universität Zürich)- 11:30
- 11:55
- 12:20
- 12:45
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11:30
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13:00
Higgs physics Auditorium
Auditorium
DESY Hamburg
Conveners: Matthias Schröder (KIT), Sarah Heim (DESY), Vincent Theeuwes (University of Goettingen)- 11:30
- 11:50
- 12:10
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11:30
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13:00
Physics beyond the SM SR 4a
SR 4a
DESY Hamburg
Conveners: Alexander Mann (Ludwig-Maximilians-Universität München), Frank Ellinghaus, Samuel Bein (University of Hamburg), Dr Saranya Samik Ghosh (RWTH Aachen University), Prof. Thorsten Ohl (Universität Würzburg)-
11:30
Light stops, heavy gluinos, and a novel solution to the little hierarchy problem 15mRadiative corrections with new heavy particles coupling to Higgs doublets destabilize the electroweak scale and require an ad-hoc counterterm cancelling the large loop contribution. If the mass scale m1 of these new particles in in the TeV range, this feature constitutes the "little fine-tuning problem". We consider the case that the new-physics spectrum has a little hierarchy with two particle mass scales m1, m2 and m2 = O(10 m1) and no tree-level couplings of the heavier particles to Higgs doublets. As a concrete example we study the (next-to-)minimal supersymmetric standard model ((N)MSSM) for the case that the gluino mass M3 is significantly larger than the stop mass parameters m_{L,R} and show that the usual one-loop fine-tuning analysis breaks down. If m_{L,R} is defined in the dimensional-reduction (DR-bar) or any other fundamental scheme, corrections enhanced by powers of M3^2/m_{L,R}^2 occur in all higher loop orders. After resumming these terms we find the fine-tuning measure substantially improved compared to the usual analyses with M3 <~ m_{L,R}. In our hierarchical scenario the stop self-energies grow like M3^2, so that the stop masses m_{L,R}^{OS} in the on-shell (OS) scheme are naturally much larger than their DR-bar counterparts m_{L,R}^{DR-bar}. This feature permits a novel solution to the little fine-tuning problem: DR-bar stop masses are close to the electroweak scale, but radiative corrections involving the heavy gluino push the OS masses, which are probed in collider searches, above their experimental lower limits. As a byproduct, we clarify which renormalization scheme must be used for squark masses in loop corrections to low-energy quantities such as the B-B-bar mixing amplitude.Speaker: Prof. Ulrich Nierste (Karlsruhe Institute of Technology)
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12:10
Search for Higgsino production in SUSY scenarios with a compressed mass spectrum 15mA search for leptonic decays of Higgsino-like neutralinos in the case of a compressed mass spectrum using a track, a reconstructed lepton and missing transverse momentum is presented. We consider the case of a second-lightest neutralino decaying into a dark matter candidate - lightest neutralino - and two leptons via an off-shell Z boson. In the case of a very small mass differences between the neutralinos, the leptons produced are very soft, making it very difficult to reconstruct them at CMS. We consider a case where one of the leptons is reconstructed by a track, and the other as a reconstructed lepton of opposite charge. Signals of different mass splitting are probed and interpreted within a set of simplified models. Multivariate discriminants are employed in the event- and object-level selection, and their performance is studied.Speaker: Mr Yuval Nissan (Experimental Particle Group)
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12:30
Anomalous magnetic moments from asymptotic safety 15mThe measurements of the muon and electron anomalous magnetic moments hint at physics beyond the standard model. We explain why asymptotically safe extensions based on an enlarged scalar sector and Yukawa couplings between leptons and new vector-like fermions explain the data naturally. Models stabilize the Higgs potential, predict the tau anomalous magnetic moment, and feature new particles in the TeV energy range whose signatures at colliders are indicated. With small CP phases, the electron EDM can be as large as the present bound.Speaker: Mrs Clara Hormigos-Feliu (TU Dortmund)
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11:30
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11:30
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13:00
Standard Model SR 3
SR 3
DESY Hamburg
Conveners: Joany Manjarres Ramos (Technische Universität Dresden), Patrick Connor (DESY), Sven-Olaf Moch (UHH)-
11:30
Dipole subtraction at next-to-leading order in nonrelativistic-QCD factorization 25mAbstract: "We describe an implementation of a subtraction scheme in the nonrelativistic-QCD treatment of heavy-quarkonium production at next-to-leading-order in the strong-coupling constant, covering S- and P-wave bound states. It is based on the dipole subtraction in the massless version by Catani and Seymour and its extension to massive quarks by Phaf and Weinzierl. Important additions include the treatment of heavy-quark bound states, in particular due to the more complicated infrared-divergence structure in the case of P-wave states." Reference: arXiv:1909.03698Speaker: Dr Mathias Butenschön (Universität Hamburg)
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11:55
Recent NNLO PDF fits with HERA jet data 25mAbstract: The HERA collaborations H1 and ZEUS have performed new PDF fits including their latest jet data. A joint PDF fit of H1 and ZEUS jet and inclusive data is performed in the HERAPDF style at NNLO QCD. Scale uncertainties are reduced significantly with respect to the corresponding fit at NLO. The preliminary result is alpha_S(M_Z)=0.1150 +/-0.0008(exp) +0.0002-0.0005(mode/param) +/-0.0006 (hadr) +/-0.0027 (scale). The H1 collaboration performed a PDF fit of inclusive diffractive data together with diffractive jet data at NNLO QCD. This results in a more precise determination of diffractive parton densities and improved predictions of diffractive jet production cross sections.Speaker: Dr Katarzyna Wichmann (DESY)
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11:30
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11:30
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13:00
Top physics SR 1
SR 1
DESY Hamburg
Conveners: Dr Andrea Knue (University of Freiburg), Nils Faltermann (KIT)- 11:30
- 11:50
- 12:10
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13:00
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14:00
Lunch 1h
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14:00
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16:30
Computing: Machine Learning SR 1
SR 1
DESY Hamburg
Conveners: Paul Glaysher (DESY), Yannik Rath (RWTH Aachen University)- 14:00
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14:25
Adversarial classifier for ttH(bb) in ATLAS 20mThe ATLAS ttH(bb) analysis is limited by the background modelling uncertainties, that result in a bias of the classifier towards the Monte Carlo generator used for training. We apply adversarial domain adaptation to train a more generic classifier. We employ a neural network that simultaneously classifies the signal versus background events, while minimizing the difference of the classifier response to two alternative background MC models.Speaker: José Manuel Clavijo Columbié (DESY)
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14:45
ML for ttgamma in ATLAS 25mThrough the associated production of the ttgamma process the strength of the electromagnetic gauge coupling of the top quark and the photon can be measured. The measurement of this fundamental parameter of the Standard Model (SM) also serves as a test of the vector structure of the electromagnetic interaction and a probe to new physics beyond the SM such as potential tensor contributions. Evidence of this process was found by CDF at the Tevatron at sqrt(s) = 1.96 TeV. The process was later observed in ATLAS and CMS at sqrt(s) = 7 and sqrt(s) = 8 TeV with increased precision. Different deep neural network (DNN) approaches are used to improve the separation of signal and background processes. Binary, as well as multi-class neural networks for separating ttgamma signal processes from underlying background events and other machine learning techniques for separating individual types of backgrounds are presented using proton-proton collisions data, taken between 2015 and 2018 with the ATLAS detector. Furthermore, a neural network for separating prompt photons from fake photons is presented. Signal and background processes are hereby grouped into two or multiple different classes. A dedicated overview of machine learning techniques within the scope of a ttgamma cross section measurement is given.Speaker: Mr Steffen Korn (II Physikalisches Institut, Georg-August-Universität Göttingen)
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15:10
Attention-based reconstruction for ttH(bb) in CMS 20mA precise determination of the interactions of the Higgs boson with other SM particles is a crucial part of the LHC physics program. When determining the top Yukawa coupling in ttH(bb) events, deep learning plays an integral role. In the single-lepton channel, multivariate approaches using deep neural networks (DNNs) achieve state-of-the-art performance in signal/background classification. A particular challenge of this analysis is the discrimination of ttH(bb) events from the irreducible tt + bb background. Considering the combinatorial assignment of jets offers a possible means to deal with this problem and thus further improve performance. To achieve this, an attention-based DNN classifier (COBRA) was developed, whose results are presented in this talk.Speaker: Tobias Lösche (University of Hamburg)
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15:30
Generative Models for Calorimeter Shower Simulation (ILD) 25mIn this talk, we demonstrate the usage of Generative Adversarial Networks (GANs) and Variational Auto-Encoders (VAEs) for modeling the electromagnetic showers in the context of proposed International Large Detector (ILD), in the central region of Silicon-Tungsten (Si-W) Electromagnetic Calorimeter. After successful completion of the training processes, the properties of synthesized showers are compared to the showers from a full detector simulation using Geant4. Our results demonstrate the potential of using such networks for fast calorimeter simulation for ILD detector in the future and open the possibility to complement current simulation techniques.Speaker: Mr Engin Eren (DESY)
- 15:55
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14:00
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16:30
Flavor physics SR 4b
SR 4b
DESY Hamburg
Conveners: Dr Christoph Langenbruch (RWTH Aachen), Mr Danny van Dyk (Universität Zürich)- 14:00
- 14:25
- 14:50
- 15:15
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14:00
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16:30
Linear Collider Forum BAH1
BAH1
DESY Hamburg
Conveners: Dr Frank Simon (Max-Planck-Institute for Physics), Gudrid Moortgat-Pick (University of Hamburg / DESY), Sabine Riemann (DESY)- 14:00
- 14:30
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14:00
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16:30
Physics beyond the SM SR 4a
SR 4a
DESY Hamburg
Conveners: Alexander Mann (Ludwig-Maximilians-Universität München), Frank Ellinghaus, Samuel Bein (University of Hamburg), Dr Saranya Samik Ghosh (RWTH Aachen University), Prof. Thorsten Ohl (Universität Würzburg)-
14:00
Search for new physics with leptons in the final state 20mThis presentation is a potpourri of Aachen results searching for BSM. One key search looks for excited leptons (e* and mu*) in the contact interaction channel providing the maximum sensitivity in terms of lstar mass. To put it in context, its sensitivity in terms of mass and compositeness scale Lambda is compared with the llg channel. We also search for new heavy charged boson, W', in the classical channels with enu or munu in the final state providing the max mass reach. The decay to tau+nu is gaining interest from flavour observations similar to other searches with 3rd particles. Besides searches driven by specific models, a model unspecific search is looking at all event classes to make sure we don't miss any sign of new physics.Speaker: Dr Kerstin Hoepfner (RWTH Aachen)
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14:25
The tail of Wh: another way of probing New Physics with dibosons 15mThe lack of evidence of New Physics coming from direct searches of resonances at the LHC calls for an increase in efforts to devise new observables that can indirectly probe New Physics. If new resonances exist but are out of the reach of the LHC or future colliders, they could manifest themselves through a harder p_T spectra with respect to the SM. In this context, the diboson final state has attracted lots of attention in recent times as a great New Physics probe. In this talk, I will focus on the Wh channel, with the Higgs boson decaying to either b\bar{b} or \gamma\gamma. I will discuss the relevant backgrounds in both cases and, for the hadronic Higgs channel, the details of the jet substructure techniques used to reduce them. Moreover, I will show how taking into account properly detector effects, hadronization and B-hadron decay affects the projected bounds. Finally, I will show preliminary results for the bounds on the SMEFT dimension 6 operator this channel is most sensitive to for the b\bar{b} channel at HL-LHC for the \gamma\gamma channel at FCC.Speaker: Mr Alejo Nahuel Rossia (DESY, HU Berlin)
- 14:45
- 15:05
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14:00
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16:30
Standard Model SR 3
SR 3
DESY Hamburg
Conveners: Joany Manjarres Ramos (Technische Universität Dresden), Patrick Connor (DESY), Sven-Olaf Moch (UHH)-
14:00
A precise W pT measurement using ATLAS low-mu data 25mAbstract: Theoretical predictions of the W-boson mass via the electroweak fit are now more precise than any experimental measurement. The recent measurement by the ATLAS collaboration suffered from large uncertainties from pT(W) modelling and pileup. In 2017 and 2018 ATLAS ran under special low pileup (“low-mu”) conditions at 13TeV and 5TeV, providing respectively 339pb^-1 and 256pb^-1 of data which will be valuable for precision W physics. This talk presents the efforts and preliminary results in using this low-mu data to measure pT(W) with %-level precision, and prospects towards its use in a future W-boson mass measurement.Speaker: Mr Harry Lyons (DESY)
- 14:25
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14:50
Pileup mitigation techniques in CMS 25mAbstract: Every bunch crossing at the LHC has not only one proton-proton interaction but several. These additional proton-proton interactions are called pileup interactions. With the increasing luminosity of the LHC also the number of pileup interactions per bunch crossing increased in the past years and it will reach up to 140 pileup interaction during high-luminosity LHC operation. Removing the pileup from an event is essential because pileup does not only affect the jet energy but also other event observables as for example the missing transverse energy, the jet substructure, jet counting, and the lepton isolation. To account for these pileup effects various techniques like-charged hadron subtraction, pileup jet ID, delta-beta correction for lepton isolation are used within CMS, but meanwhile, a new technique, PUPPI, has been introduced and extensively tested on 2016 data. This talk will explain the algorithm behind PUPPI and shows the first Data to MC comparison plots of the variables of PUPPI.Speaker: Anna Benecke (University of Hamburg)
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15:15
Precision measurement of Triple Gauge Couplings at future electron-positron colliders 25mAbstract: With the lack of hints of new physics at high energies the focus of particle physics has started turning to precision measurements to detect small deviations from the expectations of the Standard Model. Complementary to the HL-LHC, a future electron-positron collider with energies at the electroweak symmetry breaking (EWSB) scale could enable such precise tests in the Higgs-, Electroweak- and top-sectors. Multiple proposals for such a collider are currently under discussion. Their designs vary most prominently in the center-of-mass energy, the luminosity at those energies and the availability of polarisation of either beam. The influence of these quantities on the precision of measurements informs which characteristics are desirable in a future collider. In the projection of sensitivities of electron-positron colliders, the contact interaction of three gauge bosons takes an important role. Anomalies in the triple gauge boson couplings (TGCs) could hint towards new physics in the gauge boson sector. In addition, the measured TGCs enter into signal and background estimations of Higgs coupling measurements and must be strongly constrained. Possible anomalous deviations in the TGCs can be quantified in a generic way using an effective field theory (EFT) approach. Fitting anomalous TGCs to data requires the use of final state measurements which are also used to determine beam polarisation and chiral cross-sections. Due to this overlap, a parallel fit of all these parameters is required. Such a fit has been set up and uses multi-dimensional differential cross-sections to fit TGC, chiral cross-section, and polarisation parameters. Results of this fit are presented for different setups of possible electron-positron colliders at the EWSB-scale energies, with a focus on the influence of polarisations and luminosity.Speaker: Mr Jakob Beyer (DESY)
- 15:40
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14:00
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14:00
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16:30
Top + X Auditorium
Auditorium
DESY Hamburg
Conveners: Dr Andrea Knue (University of Freiburg), Matthias Schröder (KIT), Nils Faltermann (KIT), Sarah Heim (DESY), Vincent Theeuwes (University of Goettingen)- 14:00
- 14:20
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16:30
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16:45
Coffee break 15m
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16:45
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18:00
Seminar Talk: Quantum technologies for high energy physics Auditorium
Auditorium
DESY Hamburg
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16:45
Quantum Computing 45mSpeaker: Simone Montangero
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16:45
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18:00
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19:00
Institute Assembly SR 4a
SR 4a
DESY Hamburg
Convener: Ties Behnke (DESY)-
18:00
Institute Assembly 1hhttps://indico.desy.de/indico/event/24866/
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18:00
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19:00
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22:00
Workshop Dinner 3h
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- 09:00 → 10:25
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10:30
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11:00
Coffee break 30m
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11:00
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13:00
Computing SR 4b
SR 4b
DESY Hamburg
Conveners: Christoph Wissing (DESY), Rene Caspart (KIT - Karlsruhe Institute of Technology (DE))- 11:00
- 11:20
- 11:40
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11:00
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13:00
Higgs physics Auditorium
Auditorium
DESY Hamburg
Convener: Vincent Theeuwes (University of Goettingen)- 11:00
- 11:20
- 11:40
- 12:00
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11:00
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13:00
Physics beyond the SM SR 4a
SR 4a
DESY Hamburg
Conveners: Alexander Mann (Ludwig-Maximilians-Universität München), Frank Ellinghaus, Samuel Bein (University of Hamburg), Dr Saranya Samik Ghosh (RWTH Aachen University), Prof. Thorsten Ohl (Universität Würzburg)-
11:00
Supersymmetric Higgs Inflation at Colliders 15mWe study a scale-invariant minimal supersymmetric Standard Model which allows for an implementation of inflation in the early universe. This model has the same field content as the Next-to-Minimal Supersymmetric Standard Model (NMSSM) thus can be distinguished by observations in the scalar sectors. A crucial role play the singlet components. We point out that there might exist light singlet-like states with a different phenomenology from the ordinary (Z3-invariant) NMSSM.Speaker: Dr Wolfgang Gregor Hollik (KIT)
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11:20
Search for SUSY in events with same-flavor opposite-charge dileptons, jets, and missing transverse momentum at CMS 15mThe current status of a search for supersymmetry (SUSY) in events with same-flavor opposite-sign lepton pairs is presented. The analysis utilizes data recorded by the CMS detector from 2016 to 2018. As the considered signals include strong production of SUSY particles, jets are also required, along with large missing transverse momentum, which arises from undetected LSPs. An important feature of the analysis is the use of a likelihood variable which is used to discriminate between top-pair production and SUSY events.Speaker: Mr Marius Teroerde (RWTH Aachen University)
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11:40
Chargino search at the ILC 15mThe lighter chargino (chi1) is a prime candidate to be the next-to-lightest SUSY particle (the NLSP). Several analyses have been done of chi1 pair-production at the ILC, at specific model-points, showing that detection and property-determination is possible, even for very difficult cases. However, no recent studies have evaluated the reach of the ILC to detect chi1 pair production in general. In this contribution, cross sections for chi1 production at the ILC were evaluated with a wide range of parameters. The aim of the study was to determine the conditions for the lowest cross sections and compare these worst-case values with an estimation of the cross section limit for the observation of the lightest charginos at the ILC. The estimated limits were extrapolated from the studies performed at LEP, which can also be regarded as a worst-case scenario.Speaker: Dr María Teresa Núñez Pardo de Vera (DESY)
- 12:00
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13:05
Standard Model SR 3
SR 3
DESY Hamburg
Conveners: Joany Manjarres Ramos (Technische Universität Dresden), Patrick Connor (DESY), Sven-Olaf Moch (UHH)-
11:00
Nested soft-collinear subtractions in NNLO QCD computations 25mAbstract: Currently important progress is being made in next-to-next-to-leading order (NNLO) QCD calculations. As a result, many processes at hadron colliders have been computed to NNLO QCD precision. Despite these developments, the search for the optimal subtraction scheme that allows us to handle IR and collinear singularities in an efficient and general way is still ongoing. In this talk I will introduce the nested soft-collinear subtraction scheme that possesses many desired features; for example, it is analytic, fully local and highly modular. I will further describe an application of this scheme to deep inelastic scattering that, together with the description of color singlet production and decay, completes the set of building blocks that are required for the application of this scheme to arbitrary processes at hadron colliders.Speaker: Konstantin Asteriadis (Institute for Theoretical Particle Physics, Karlsruhe Institute of Technology)
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11:25
Evolution of single and double parton densities with ChiliPDF 25mAbstract: We present a method to discretize and numerically solve the DGLAP evolution equations, using Chebyshev interpolation. This allows for high numerically accuracy with grids of quite a moderate size. We demonstrate the power of this method, implemented in the C++ library ChiliPDF, both for conventional PDFs and for double Parton distributions, which appear in the description of double-parton interactions.Speaker: Mr Riccardo Nagar (University of Milan Bicocca)
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12:40
Double prompt J/psi hadroproduction in the Parton Reggeization approach with high-energy resummation 25mAbstract: We study double prompt J/ψ hadroproduction within the nonrelativistic-QCD factorization formalism adopting the parton Reggeization approach to treat initial-state radiation in a gauge invariant and infrared-safe way. We present first predictions for the cross section distributions in the transverse momenta of the subleading J/ψ meson and the J/ψ pair. Already at leading order in α_s, these predictions as well as those for the total cross-section and its distributions in the invariant mass $m_{\psi\psi}$ and the rapidity separation |Y| of the J/ψ pair nicely agree with recent ATLAS and CMS measurements, except for the large $m_{\psi\psi}$ and large-|Y| regions, where the predictions substantially undershoot the data. In the latter regions, BFKL resummation is shown to enhance the cross sections by up to a factor of two and so to improve the description of the data.Speaker: Dr Zhiguo He (Hamburg University)
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11:00
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11:00
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13:00
Top physics SR 1
SR 1
DESY Hamburg
Conveners: Dr Andrea Knue (University of Freiburg), Nils Faltermann (KIT)- 11:00
- 11:20
- 11:40
- 12:00
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13:00
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14:00
Lunch break 1h
- 14:00 → 15:30