Loops and Legs in Quantum Field Theory

29 Apr 2018, 16:00 → 4 May 2018, 14:30 Europe/Berlin

D-56329 St. Goar, Germany

14th Workshop organized by the Theory Group, DESY, Zeuthen 

Photo: H. Klaes

Sunday, 29 April

16:00 → 18:00 Registration

18:00 → 19:00 Dinner

19:30 → 21:00 Reception

Monday, 30 April

09:20 → 10:30 Plenary 1

09:20 Welcome

Speaker: Prof. Johannes Bluemlein (DESY)

09:30 Jet cross sections with NNLOJET

In my talk, I would like to review the phenomenology of LHC observables related to processes newly implemented in the NNLOJET parton level generator.

Speaker: Prof. Aude Gehrmann-De Ridder (ETH, Zurich)

Slides gehrmann_LL18.pdf

10:00 Threshold and jet radius joint resummation for single-inclusive jet production

Speaker: Sven-Olaf Moch (UHH)

Slides moch-ll2018.pdf

10:30 → 11:00 Coffee break

11:00 → 13:00 Plenary 1

11:00 NNLO corrections to VBF Higgs production

Higgs production through Vector Boson Fusion (VBF) is the most important tree level production channel for Higgs production at the LHC. We present NNLO QCD corrections to differential distributions of H+2j in VBF using the antenna subtraction formalism.

Speaker: Mr Juan Cruz-Martinez (IPPP Durham)

Slides juan.pdf

11:30 Non-resonant and electroweak corrections to top pair production

Speaker: Andreas Maier (IPPP, Durham University)

Slides Andreas_Maier_LL2018.pdf

12:00 Elliptic polylogarithms and two-loop Feynman integrals

Speaker: Dr Claude Duhr (CERN)

Slides Duhr_LL18.pdf

12:30 Applications of integrand reduction to 5-gluon 2-loop scattering amplitudes in QCD

Speaker: Simon Badger (Edinburgh)

Slides badger_LL2018.pdf

13:00 → 14:30 Lunch

14:30 → 16:00 Parallel 1

14:30 Charm and Bottom Quark Masses: an Update

Speaker: Prof. Johann Kuehn (KIT)

Slides KuehnLL2018.pdf

15:00 No-$\pi^2$ Theorem for Euclidean Massless Correlators

Speaker: Dr Konstantin Chetyrkin (Institut für Theoretische Teilchenphysik, KIT)

Slides Chetyrkin_LL18.pdf

15:30 The massive 3-loop form factor in the planar limit

Speaker: Dr Narayan Rana (DESY)

Slides RanaLL18.pdf

14:30 → 16:00 Parallel 2

14:30 Pentagon functions for non-planar scattering amplitudes

Speaker: Prof. Johannes Henn (JGU Mainz)

Slides 2018_04_30_henn_talk_LL2018_stgoar.pdf

15:00 Progress in the calculation of the complete set of two-loop five-point master integrals

Speaker: Dr Konstantinos Papadopoulos (NCSR DEMOKRITOS)

Slides ll2018.pdf

15:30 Planar Two-Loop Five-Gluon Amplitudes from Numerical Unitarity

Speaker: Dr Ben Page (Freiburg University)

Slides LoopsAndLegs2018.pdf

16:00 → 16:30 Coffee break

16:30 → 18:30 Parallel 1

16:30 Electroweak radiative corrections to polarized Bhabha scattering

Speaker: Dr Andrei Arbuzov (JINR)

Slides arbuzov_LL_2018.pdf

17:00 Electroweak corrections in the Two-Higgs-Doublet Model and Singlet Extensions of the Standard Model

Speaker: Prof. Stefan Dittmaier (University of Freiburg)

Slides dittmaier-ll18.pdf

17:30 Anomalous triple-gauge-boson interaction in vector-boson pair production with Recola2

Diboson production processes are of great importance in high-energy physics. On one hand, they are sensitive to the gauge-boson self interaction so that their measurement is a crucial test of the Standard Model (SM) description of the gauge-boson dynamics. On the other hand, diboson production at the LHC is a source of background for other SM processes as well as for direct New Physics (NP) searches. Therefore a precise theoretical knowledge of these processes is mandatory not only in view of precision tests of the SM but also in the one of the NP searches. We compute the NLO QCD and NLO electroweak corrections to diboson production processes at the LHC including the effect of the anomalous triple-gauge-boson interactions at NLO QCD accuracy. The anomalous triple-gauge-boson interactions are parametrized in terms of higher-dimension operators in the effective field theory (EFT) framework. Our calculation is the first application of Recola2 to EFT models.

Speaker: Mauro Chiesa (University of Würzburg)

Slides diboson_chiesa.pdf

18:00 Analytic tools for IR subtraction beyond NLO

Speaker: Prof. Lorenzo Magnea (University of Torino)

Slides 07-Loops&Legs18.pdf

16:30 → 18:30 Parallel 2

16:30 The rho-parameter at three loops and elliptic functions

Speaker: Abilio De Freitas (DESY)

Slides LL2018_Abilio.pdf

17:00 Some 4-loop results on QCD cusp anomalous dimension

Speaker: Dr Andrey Grozin (Budker Institute of Nuclear Physics)

Slides LL2018_Grozin.pdf

17:30 Numerical evaluation of two-loop amplitudes

Speaker: Mr Stephan Jahn (Max Planck Institute for Physics)

Slides presentation.pdf

18:00 Four gluon Scattering Amplitude at Three Loops in QCD

Speaker: Dr Taushif Ahmed (Mainz University)

Slides LoopsAndLegs2018-Ahmed.pdf

18:30 → 19:30 Dinner

Tuesday, 1 May

09:00 → 10:30 Parallel 3

09:00 Fully Differential Higgs Pair Production in Association With a Vector Boson at NNLO in QCD

We present a fully differential next-to-next-to-leading order calculation of the Higgs pair production in association with a Z boson, which is important for probing the trilinear Higgs self-coupling. The next-to-next-to-leading-order corrections enhance the next-to-leading order total cross sections by a factor of 1.2∼1.5, depending on the collider energy, and change the shape of next-to-leading order kinematic distributions. We discuss how to determine the trilinear Higgs self-coupling using our results.

Speaker: Dr Jian Wang (Technical University of Munich)

Slides vhh_JW_LL2018.pdf

09:30 Double Higgs Production in the High Energy Limit

Speaker: Mr Joshua Davies (University of Liverpool)

Slides davies.pdf

10:00 Top quark mass effects in HJ production at NLO

Speaker: Dr Matthias Kerner (Max-Planck-Institut für Physik, München)

Slides LoopsAndLegs2018_Kerner.pdf

09:00 → 10:30 Parallel 4

09:00 The Z boson resonance at 2 loops

Speaker: Janusz Gluza (Silesia University)

Slides 01-ll2018_gluza.pdf

09:30 Five-particle phase-space integrals in QCD

Speaker: Oleksandr Gituliar (Universität Hamburg)

Slides Gituliar LL18

10:00 Precise determination of the strong coupling from energy-energy correlation

In this talk we present a determination of the strong coupling from a fit of QCD predictions for energy-energy correlation measured in electron-positron collisions at various center-of-mass energies. Experimental data are compared to precise theoretical calculations incorporating NNLO predictions combined with NNLL resummation in the back-to-back region. Hadronization corrections are assessed using modern shower Monte Carlo programs matched to NLO fixed-order computations.

Speaker: Zoltán Tulipánt (University of Debrecen)

Slides EECMC_LL2018.pdf

10:30 → 11:00 Coffee break

11:00 → 13:00 Parallel 3

11:00 Sector-improved residue subtraction: Improvements and Applications

Speaker: Arnd Behring (DESY Zeuthen)

Slides ll2018-talk.pdf

11:30 Precision calculations in new physics models

Speaker: Dominik Stoeckinger (TU Dresden)

Slides 2018MayLL.pdf

12:00 Multi-Loop Amplitudes in the High-Energy Limit in N = 4 SYM

Speaker: Robin Marzucca (UCLouvain)

Slides LL18_Robin_Marzucca.pdf

12:30 On the evaluation of scattering amplitudes with massive particles

Speaker: Dr Amedeo Primo

Slides LL18_Primo.pdf

11:00 → 13:00 Parallel 4

11:00 Loop-tree duality at two loops

Speaker: Dr German Rodrigo (IFIC-S8a Valencia)

Slides 2018_05_rodrigo_duality_LL.pdf

11:30 On the gauge dependence of Quantum Electrodynamics

Speaker: Henry Kißler (HU Berlin)

Slides kisslerLL18.pdf

12:00 Top pair production at NNLO

Speaker: Mr Sebastian Sapeta (IFJ PAN, Kraków)

Slides sapeta-ll18.pdf

12:30 Loopedia, a database for loop integrals

Speaker: Dr Thomas Hahn (Max-Planck Institut für Physik München)

Slides hahn.pdf

13:00 → 14:30 Lunch

14:30 → 16:00 Parallel 5

14:30 Multiloop Euler-Heisenberg Lagrangians, Schwinger pair creation and the QED photon amplitudes

Speaker: Prof. Christian Schubert (Instituto de Fisica y Matematicas, Universidad Michoacana de San Nicolas de Hidalgo)

Slides LL2018schubert.pdf

15:00 On the Adaptive Integrand Decomposition of Two-loop Scattering Amplitudes

Speaker: William Javier Torres Bobadilla (IFIC CSIC-UV)

Slides LL2018.pdf

15:30 Conformal Symmetry and Feynman Integrals

Speaker: Mr Simone Zoia (Johannes Gutenberg University Mainz)

Slides zoia_LoopsLegs2018.pdf

14:30 → 16:00 Parallel 6

14:30 NNLO Corrections to W Boson Production

The inclusive production of leptonically decaying W bosons at the LHC is an important reference process for many analyses, and is relevant to our knowledge of the structure of the proton. We will present the results from a calculation of the W boson transverse momentum distribution at NNLO QCD using the method of antenna subtraction.

Speaker: Mr Duncan Walker (IPPP, Durham University)

Slides wpt.pdf

15:00 Regge limit of scattering amplitudes from an anomalous dimension

Speaker: Robin Brüser (Mainz University)

Slides Robin_Brueser_LL2018.pdf

15:30 Threshold resummation in rapidity for colorless particle production at the LHC

We present a formalism that resums threshold enhanced logarithms to all orders in perturbative Quantum Chromodynamics for the rapidity distribution of any colorless particle produced in hadron colliders. We achieve this by exploiting the factorization properties and K+G equations satisfied by the soft and virtual parts of the cross section. We compute for the first time, the resummed result in two dimensional Mellin space up to next-to-next-to-next-to-leading logarithmic (N3LL) accuracy. Using various state-of-the-art multi-loop and multi-leg results, we demonstrate the numerical impact of the resummed results up to next-to-next-to-leading order for the rapidity distribution of the Higgs boson and Drell-Yan production at the Large Hadron Collider. We find that these threshold logs in the resummed result stabilise the predictions against the renormalization and factorization scale choices as well as we achieve better perturbative convergence.

Speaker: Dr Goutam Das (DESY, Hamburg)

Slides GoutamLL2018.pdf

16:00 → 16:30 Coffee break

16:30 → 18:00 Parallel 5

16:30 Infrared singularities of QCD scattering amplitudes in the Regge limit to all orders

Speaker: Mr Leonardo Vernazza (Institute für Theoretische Physik E, RWTH Aachen)

Slides LVernazza.pdf

17:00 Scheme and gauge dependence of the generalized Crewther relation in perturbative QCD

Speaker: Andrei Kataev (Insitute for Nuclear Research of the RAS)

Slides Kataev-Molokoedov-LL-2018.pdf

17:30 NLO QCD Energy-Energy-Correlations in $e^+ e^-$ Annihilation

Speaker: Dr Vladyslav Shtabovenko (Zhejiang University Hangzhou)

Slides EECatNLO.pdf

16:30 → 18:00 Parallel 6

16:30 Automated calculation of soft functions in SCET

Speaker: Dr Bahman Dehnadi (University of Siegen)

Slides Dehnadi-Loops&Legs2018.pdf

17:00 On-the-fly reduction of open loops

Speaker: Dr Max Zoller (University od Zurich (UZH))

Slides Zoller_LL_2018.pdf

17:30 MBnumerics: Numerical integration of Mellin-Barnes integrals in physical regions

Speaker: Johann Usovitsch (DESY Zeuthen)

Slides Usovitsch.pdf

18:00 → 19:00 Dinner

20:00 → 21:30 Concert

Wednesday, 2 May

09:00 → 10:30 Plenary 2

09:00 Hopf algebra for Feynman diagrams and integrals

Speaker: Ruth Britto (Trinity College Dublin)

Slides Britto_LL2018.pdf

09:30 3-loop coupling for hot gauge theory

Speaker: Dr York Schröder (Universidad del Bio-Bio)

Slides talkLL18.pdf

10:00 NNLO Parton Distributions for the LHC

Speaker: Sergey Alekhin (DESY)

Slides alekhin.pdf

10:30 → 11:00 Coffee break

11:00 → 13:00 Plenary 2

11:00 Anomalous dimensions and splitting functions beyond NNLO

Speaker: Prof. Andreas Vogt (University of Liverpool)

Slides av-ll18.pdf

11:30 Two-mass 3-loop effects for heavy flavor deep inelastic scattering

Speaker: Kay Schönwald (DESY)

Slides LL2018.pdf

12:00 Computer algebra tools for Feynman integrals and related multi-sums

Speaker: Dr Carsten Schneider (RISC, J. Kepler University Linz)

Slides LoopsLegs18.pdf

12:30 Quadratic relations between Feynman integrals

Speaker: Dr David Broadhurst (Open University, UK)

Slides broadhurst_ll2018.pdf

13:00 → 14:30 Lunch

15:00 → 18:00 Excursion

18:30 → 19:30 Dinner

Thursday, 3 May

09:00 → 10:30 Parallel 7

09:00 Off-shell Top Quarks with a Jet or a Photon

Speaker: Dr Malgorzata WOREK (RWTH Aachen University)

Slides mworek.pdf

09:30 kT-dependent factorization at one loop

Speaker: Andreas van Hameren (IFJ PAN)

Slides vanhameren.pdf

10:00 Automated calculation of e+e- -> BSM BSM

Speaker: Sven Heinemeyer (IFCA (CSIC, Santander))

Slides sven.pdf

09:00 → 10:30 Parallel 8

09:00 The HEPGAME project

Speaker: Dr Jos Vermaseren (Nikhef)

Slides landl18.pdf

09:30 Cuts and Feynman amplitudes beyond polylogarithms

In this talk I will present some of the newest advancements in the calculation of multiloop Feynman amplitudes beyond multiple polylogarithms. In particular, I will show how to solve higher order irreducible differential equations for non-polylogarithmic Feynman integrals and how to write their solution in terms of a suitable basis of functions. I will also comment on the difficulties in embedding these integrals into physically relevant scattering amplitudes for the calculation of important observables for the LHC.

Speaker: Lorenzo Tancredi (KIT Karlsruhe)

Slides LL2018_tancredi.pdf

10:00 An improved Algorithm to compute Inverse Mellin Transforms of Nested Binomial Sums

Speaker: Jakob Ablinger (Johannes Kepler Universität Linz)

Slides talk.pdf

10:30 → 11:00 Coffee break

11:00 → 13:00 Parallel 7

11:00 The next generation of OpenLoops

Speaker: Philipp Maierhöfer (University of Zürich)

Slides maierhoefer.pdf

11:30 $\gamma_{5}$ in FDH

In this talk, we review recent developments of the four-dimensional helicity scheme (FDH) in higher-order calculations, mainly focusing on the consistent treatment of $\gamma_{5}$. We start with distinctive examples and demonstrate that at the one-loop level the recently proposed four-dimensional formulation (FDF) of FDH constitutes a viable and efficient alternative to more traditional approaches. Apart from this, we provide a comprehensive definition of an anticommuting $\gamma_{5}$ in FDH and discuss when it is convenient to use it in FDH multi-loop calculations.

Speaker: Christoph Gnendiger (PSI)

Slides LL2018_gnendiger.pdf

12:00 NLO mixed QCD-EW corrections to Higgs gluon fusion

The study of the Higgs boson properties is one of the main tasks of contemporary high-energy physics. Among Higgs properties, its interaction with gluons is interesting since it can be facilitated by yet unknown elementary particles. One of the major sources of uncertainty in the theoretical description of $ggH$ coupling originates from mixed QCD-electroweak contributions. The NLO QCD corrections to these contributions were evaluated few years ago in the approximation where electroweak boson masses were considered to be significantly larger than the mass of the Higgs boson and it is desirable to compute those corrections for physical masses of gauge bosons and Higgs boson. In this talk, I will present a major step towards this goal and describe the analytic evaluation of NLO mixed QCD-EW three-loop virtual corrections to $gg \to H$.

Speaker: Mr Marco Bonetti (TTP KIT)

Slides LL2018_BONETTI.pdf

12:30 Soft gluons and top quark pair production

Speaker: Dr Lilin Yang (Peking University)

Slides LLYang_LL2018.pdf

11:00 → 13:00 Parallel 8

11:00 Differential equations for loop integrals in Baikov representation

Speaker: Dr Kasper Larsen (University of Southampton)

Slides Talk_[Loops_and_Legs_2018].pdf

11:30 Integral relations and parametric annihilators

Speaker: Dr Erik Panzer (University of Oxford)

Slides talk.pdf

12:00 Automated extraction of UV counterterms for arbitrary local operators

Computing the anomalous dimensions of local composite operators present in both renormalisable and non-renormalisable QFTs is generally challenging due to the presence of many scales and loops. In this talk we present an extension of the local R* method which fully automates this task. By extending the local R* operation to arbitrary QFTs we, transform this problem to one of computing massless propagator integrals, suitable for efficient evaluation with the Forcer program.

Speaker: Dr Ben Ruijl (ETH Zurich)

Slides ll.pdf

12:30 Analytic Properties of Loop Integrands

Speaker: Pascal Wasser (Johannes Gutenberg Universität Mainz)

Slides LL2018_pwasser.pdf

13:00 → 14:30 Lunch

14:30 → 16:00 Parallel 10

14:30 CoLoRFulNNLO for LHC processes

CoLoRFulNNLO is a completely local subtraction scheme for computing fully differential predictions in NNLO QCD. The method has been fully worked out for processes without colored particles in the initial state and has shown its many strengths when it was applied to three-jet production in electron-positron annihilation. In my talk, I will present the extension of the scheme to hadron initiated processes and show the first application of our method to key LHC processes.

Speaker: Dr Adam Kardos (University of Debrecen)

Slides kardos.pdf

15:00 Higgs + Jet production above the top mass threshold

Speaker: Kirill Kudashkin (Karlsruher Institut für Technologie, Institut für Theoretische Teilchenphysik)

Slides Loops_Legs2018kudashkin.pdf

15:30 Non-planar two-loop Feynman integrals contributing to H+j production at NLO

Speaker: Hjalte Frellesvig (NCSR Demokritos)

Slides HjalteStGoar.pdf

14:30 → 16:00 Parallel 9

14:30 The corolla polynomial: a graph polynomial on half-edges

Speaker: Prof. Dirk Kreimer (Humboldt University Mathematics and Physics)

Slides KreimerLL2018.pdf

15:00 From elliptic curves to Feynman integrals

Speaker: Dr Stefan Weinzierl (Univ. Mainz)

Slides stgoar.pdf

15:30 Loop calculations for models of graphene

Speaker: John Gracey (University of Liverpool)

Slides sgoa18.pdf

16:00 → 16:30 Coffee Break

16:30 → 18:00 Parallel 10

16:30 Three-loop effective potential

Speaker: Bernd Kniehl (II. Inst. f. Theor. Phys., Univ. Hamburg)

Slides veretin.pdf

17:00 Properties of scattering forms for Yang-Mills amplitudes

Speaker: Leonardo de la Cruz (The University of Edinburgh)

Slides StGoar-Loops-Legs-Scattering-Forms.pdf

17:30 Multi-loop amplitudes and numerical unitarity

Speaker: Prof. Fernando Febres Cordero (Unversity of Freiburg)

Slides LL2018_FFC.pdf

16:30 → 18:00 Parallel 9

16:30 Gross-Neveu-Yukawa Models at Four Loops

Speaker: Dr Nikolai Zerf (ITP University of Heidelberg)

Slides 04-GNY4L_Zerf.pdf

17:00 Evaluating `elliptic' master integrals at special kinematic values: using differential equations and their solutions via expansions near singular points

Speaker: Vladimir Smirnov (Skobeltsyn Institute of Nuclear Physics of Moscow State University)

Slides smirnov.pdf

17:30 New Results in four-loop QED

Speaker: Dr Stefano Laporta (University Padova)

Slides 06-laporta_ll2018_mix.pdf

19:30 → 22:30 Conference dinner

Friday, 4 May

09:00 → 10:30 Plenary 3

09:00 Scalar one-loop Feynman integrals in arbitrary space-time dimension

Speaker: Dr Tord Riemann (DESY)

Slides riemann-ll2018-slides.pdf

09:30 High energy limit of QCD beyond Sudakov approximation

Speaker: Prof. Alexander Penin (University of Alberta)

Slides ll18.pdf

10:00 Precision studies of vector boson production with heavy quarks

Speaker: Prof. Laura Reina (Florida State University)

Slides ll2018.pdf

10:30 → 11:00 Coffee break

11:00 → 13:00 Plenary 3

11:00 Higher order and top mass effects in Higgs boson pair production within and beyond the Standard Model

Speaker: Gudrun Heinrich (Max Planck Institute for Physics)

Slides LL2018_GH.pdf

11:30 Two-loop unitarity and dual conformal symmetry

We show that the power of generalized unitarity cuts extends beyond the construction of integrands. Both integration-by-parts identities and differential equations can be derived on unitarity cuts, using tangent vectors of unitarity cut surfaces. We present applications, from the extraction of symbol alphabets for nonplanar two-loop five-point integrals to the evaluation of UV divergences in 5-loop supergravity. A surprising connection with dual conformal symmetry is presented, which offers an analytic alternative to computational algebraic geometry, and also shines light on the generalization of dual conformal symmetry to nonplanar integrals.

Speaker: Mao Zeng (UC Los Angeles)

Slides Loops_and_Legs.pdf

12:00 Form factors in QCD

Speaker: Prof. Matthias Steinhauser (KIT)

Slides ll18.pdf

12:30 Generalised cuts and Wick rotations

Speaker: Ettore Remiddi (DIFA and INFN, Bologna)

Slides remiddiLL2018.pdf

13:00 → 14:30 Lunch