QCD@LHC 2018

27 Aug 2018, 08:30 → 31 Aug 2018, 15:25 Europe/Zurich

Potthoff-Bau (TU Dresden)

Dominik Stöckinger (Technische Universitaet Dresden (DE)), Frank Siegert (Technische Universitaet Dresden (DE))

QCD@LHC 2018

27th - 31st August 2018, Dresden, Germany

Thanks to all participants for joining us for QCD@LHC 2018 in Dresden. We hope you had safe travels home and are looking forward to QCD@LHC 2019 in Buffalo from July 15-19 (note the changed date!).

Best,
Dominik and Frank

 

Welcome to the 9th edition of the international QCD@LHC workshop, which aims at fostering discussions and collaboration between experimenters and theorists, working on strong interactions at the LHC.

Topics to be discussed include:

• Latest results from the LHC on Soft and Hard QCD 
• Theory of Jets
• Parton Density Functions
• Higher Order Calculations
• Event Simulations
• Resummation
• Top Physics
• Higgs Physics
• QCD for BSM studies

Confirmed plenary contributions include:

• Jet substructure and H/V/top-tagging
  (Simone Marzani & Danilo Enoque Ferreira De Lima)
• Inclusive and dijet production at the LHC
  (Joao Pires & Bogdan Malaescu)
• QCD background processes in BSM searches
  (Jonas Lindert & Paolo Gunnellini)
• Pileup modelling and mitigation at the LHC
  (Matteo Cacciari & Satoshi Hasegawa)
• Determination of the strong coupling constant
  (Klaus Rabbertz)
• Multiloop and multileg developments
  (Stephen Jones)
• Recent developments in resummation
  (Luca Rottoli)
• Monte Carlo event generators
  (Silvan Kuttimalai)
• Recent developments for PDFs
  (Robert Thorne)
• Top production and top mass
  (Andre Hoang)
• Heavy Flavour Production at the LHC
  (Stefano Forte)
• EW corrections in the light of QCD precision
  (Marek Schönherr)
• QCD corrections for BSM signal processes
  (Anna Kulesza)
• Uncertainties and challenges in jet reconstruction
  (Aparajita Dattagupta)
• Top quark measurements in CMS
  (Till Michael Arndt)
• Vector boson(s) and jet production in ATLAS
  (Arantxa Ruiz Martinez)
• Recent results in Higgs and BSM searches in CMS
  (Dezso Horvath)
• Heavy flavour production and decay in LHCb
  (Nicola Anne Skidmore)
• Heavy Ions in ALICE
  (Livio Bianchi)

More details about the parallel tracks can be found here.

The conference is a follow-up to the successful workshops with the same name in

• Trento, Italy
• St. Andrews, Scotland 
• East Lansing, Michigan, USA 
• Hamburg, Germany 
• Suzdal, Russia 
• London, England 
• Zürich, Switzerland 
• Debrecen, Hungary

We are looking forward to welcoming you in Dresden!

Dominik and Frank for the local organisers

Interactive map

Poster.jpg

Poster.pdf

Monday, 27 August

08:30 → 09:00 Registration

09:00 → 11:00 Plenary

Convener: Alexander Glazov (Deutsches Elektronen-Synchrotron (DE))

09:00 Welcome from the organisers

09:10 Determining the strong coupling constant (45' + 10')

Speaker: Klaus Rabbertz (KIT - Karlsruhe Institute of Technology (DE))

alpha-s-from-ATLASCMS_QCDatLHC_2018_KRabbertz_final.pdf

10:05 Recent developments in PDFs (45' + 10')

Speaker: Robert Samuel Thorne (University College London (UK))

QCD@LHC18.pdf

11:00 → 11:30 Coffee break

11:30 → 13:00 Plenary

Convener: Emanuele Re (CERN)

11:30 Physics of the top quark and its mass (35' + 10')

Speaker: Andre Hoang (University of Vienna)

Hoang-Top-Plenary.pdf

12:15 Top quark measurements in CMS (35' + 10')

Speaker: Till Michael Arndt (Deutsches Elektronen-Synchrotron (DE))

QCD2018.pdf

13:00 → 14:30 Lunch

14:30 → 16:00 Heavy Quarks: Joint with EW, Higgs and BSM

Conveners: Guido Bell (University of Siegen), Jonas Lindert (University of Durham (GB)), Pietro Govoni (Universita & INFN, Milano-Bicocca (IT)), Thorsten Kuhl (Deutsches Elektronen-Synchrotron (DE))

14:30 Top quark production cross-section measurements

Measurements of the inclusive and differential cross-sections for top-quark pair and single top production cross sections in proton-proton collisions with the ATLAS detector at the Large Hadron Collider are presented at center-of-mass energies of 8 TeV and 13 TeV. The inclusive measurements reach high precision and are compared to the best available theoretical calculations. These measurements, including results using boosted tops, probe our understanding of top-pair production in the TeV regime. Measurements of the properties of the Wtb vertex in single top-quark production allow to set limits on anomalous couplings. All measurements are compared to state-of-the-art theoretical calculations.

Speaker: Knut Zoch (Georg August Universitaet Goettingen (DE))

qcd@lhc2018-top-xsec.pdf

15:00 NLO predictions for $t \bar{t}$ + $b \bar{b}$ production in association with a light-jet at the LHC

Precise measurements of Higgs boson production in association with top-quark pairs
allow for constraints on the top-quark Yukawa coupling, which in turn is crucial to fully
characterise the scalar sector of the Standard Model and could also open a window on
Beyond-the-Standard-Model interactions. At the Large Hadron Collider, searches for
$t\bar{t}H$ production in the dominant $H \to b \bar{b}$ channel are plagued by a large QCD background,
which is dominated by $t \bar{t}$ production in association with a $b \bar{b}$ pair. The detailed understanding of this multi-particle and multi-scale background process is of crucial importance for the sensitivity of $t\bar{t}H(\to b \bar{b})$ analyses.
Motivated by the fact that state-of-the-art Monte Carlo simulations for this background suffer from uncertainties related to the modeling of extra light-jet radiation, I present a study for $t \bar{t} b \bar{b}+$jet production at NLO QCD. The focus is on effects and uncertainties in observables
relevant for $t\bar{t}H(b\bar{b})$ analyses.
At the technical level this calculation represents the first application of a new on-the-fly integrand reduction algorithm implemented in OpenLoops2.

Speaker: Federico Buccioni (University of Zurich)

buccioni_QCDaLHC18.pdf

15:30 Associated top quark pair production with a Higgs boson: theoretical predictions

The investigation of the $pp \rightarrow t {\overline t} H$ process is among the highest priorities of the current LHC physics program. Correspondingly, improvements in precision with which theoretical predictions for this process are known are of central importance. In this talk the recent progress concerning theoretical predictions for the signal will be reviewed.

Speaker: Anna Katarzyna Kulesza (Westfaelische Wilhelms-Universitaet Muenster (DE))

ttH_theory18_v3.pdf

14:30 → 16:00 Monte Carlo and resummation

14:30 Herwig 7 Status and Prospects

Speaker: Andrzej Konrad Siodmok (Polish Academy of Sciences (PL))

Siodmok_Talk_Dresden.pdf

15:00 The automation of next-to-leading order electroweak calculations in MadGraph5_aMC@NLO

We discuss the automation of the calculation of leading- and next-to-leading order contributions to short-distance cross sections at hadron colliders. With the new public version of the code MadGraph5_aMC@NLO, not only NLO QCD and EW corrections but also all the subleading contributions in a mixed QCD and EW coupling expansion can now be calculated. We discuss the key features for obtaining the complete automation and we show various relevant phenomenological results that can can be obtained with the current version of MadGraph5_aMC@NLO.

Speaker: Davide Pagani (TUM - Garching bei München)

QCD_at_LHC.pdf

15:30 SHERPA: where we are and what's next

In this status report on the multi-purpose Monte-Carlo event generator Sherpa
I review recent and ongoing Sherpa studies, as well as the latest
developments of its fixed-order and all-order technologies. Fixed-order
improvements I discuss include fully automated EW corrections and support
for additional loop-induced processes. On the all-order side I cover
Sherpa's parton showers and the recent work on including NLO splitting
kernels, studying the accuracy of the showers and their on-the-fly reweighting
in state-of-the-art simulations.

Speaker: Enrico Bothmann (University of Edinburgh)

talk.pdf

14:30 → 16:00 PDFs, 𝛼ₛ and soft QCD

14:30 Double parton scattering: status of theory

I review the theory status of double parton scattering, with emhasis on higher-order raditative corrections.

Speaker: Markus Diehl (DESY)

dresden.pdf

15:00 Recent QCD results from the xFitter project

We present the xFitter project  which provides an open-source software framework
for the determination of the proton's  parton distribution functions and for the interpretation of the physics analyses in the context of  Quantum Chromodynamics.
The project has been used recently for a number of analyses performed by the LHC collaborations and theory community, which are summarised briefly. The xFitter developer’s team also performed several studies in the last year including estimation of the impact of heavy quark matching scales and next to leading log high-energy resummation in the PDF fits, which are presented in more details.

Speaker: Alexander Glazov (Deutsches Elektronen-Synchrotron (DE))

xf_qcdatlhc.pdf

15:30 NNLO QCD predictions for dijet production in diffractive DIS

Calculations for dijet production in diffractive deep-inelastic scattering (DIS) at next-to-next-to-leading order accuracy (NNLO) are presented. The calculations are based on the antenna subtraction formalism and the hard coefficients are convoluted with currently available PDFs for diffractive scattering (DPDFs).
The NNLO predictions are compared to a large number of available measurements and different observables. Detailed studies on the DPDF and scale dependencies are presented.

Speaker: Daniel Britzger (Max-Planck-Institut für Physik München)

180827-QCDLHC-britzger-NNLO-DiffDijets.pdf

14:30 → 16:00 Perturbative QCD, jets and substructure

14:30 Analytic calculation of multi-loop Feynman integrals

Multi-loop Feynman integrals represent an essential building block for the precision physics program at high-energy colliders and beyond. In my talk I will review recent developments concerning their evaluation with the method of differential equations, giving particular emphasis to the so-called canonical form and presenting some examples of phenomenological interest.

Speaker: Stefano Di Vita (Università degli Studi e INFN Milano (IT))

divita-qcd_at_lhc_2018.pdf

15:00 Differential Equations for Feynman Integrals

The calculation of Feynman Integrals is one of bottlenecks for precision calculations at Next-to-Next-to-leading order and beyond. Differential Equations have proven to be a powerful tool to relieve this bottleneck and have seen a rapid development in the last years. In this talk I will review these recent developments especially focusing on the so-called canonical form. I will present the Magnus algorithm as a tool to find these special forms. The presented techniques are then applied to several analytic calculations including part of the integrals relevant for Higgs+Jet production at three loops and for top pair production at two-loops.

Speaker: Ulrich Schubert (Argonne National Laboratory)

Schubert_QCD.pdf

15:30 Systematic approximation of multi-scale Feynman integrals

Abstract: An algorithm for the systematic analytical approximation of multi-scale Feyn-
man integrals will be discussed. The algorithm produces algebraic expressions as functions of
the kinematical parameters and mass scales appearing in the Feynman integrals, allowing
for fast numerical evaluation. The results are valid in all kinematical regions, both above
and below thresholds, up to in principle arbitrary orders in the dimensional regulator. The
scope of the algorithm will be demonstrated by presenting results for selected two-loop three-
point and four-point integrals with an internal mass scale that appear in the two-loop
amplitudes for Higgs+jet production.

Speaker: Mr Daniel Hulme (UZH)

QCD@LHC_DH.pdf

16:00 → 16:30 Coffee break

16:30 → 18:00 EW, Higgs and BSM

16:30 Determination of electroweak parameters in polarised deep-inelastic scattering at HERA

The parameters of the electroweak theory are determined in a combined electroweak and QCD analysis using all deep-inelastic $e^+p$ and $e^-p$ neutral current and charged current scattering cross sections published by the H1 Collaboration, including data with longitudinally polarised lepton beams. The mass of the $W$ boson in the on-shell scheme is determined as $\mW=80.508\pm 0.115\,\GeV$. The axial-vector and vector couplings of the light quarks to the $Z$ boson are also determined. Both results improve the precision of previous H1 determinations based on HERA-I data by about a factor of two. Possible scale dependence of the weak coupling parameters in both neutral and charged current interactions beyond the Standard Model is also studied. All results are found to be consistent with the Standard Model expectations.

Speaker: Eram Syed Rizvi (Queen Mary, University of London)

QCD@LHC-H1-2018.pdf

16:53 Mixed QCD-electroweak 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 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 these corrections for physical masses of the gauge bosons and the Higgs boson. I will present a major step towards this goal and describe first the analytic evaluation of NLO mixed QCD-EW three-loop virtual corrections to $gg \to H$, and then their implementation in the evaluation of the total cross section for $gg \to H$ in the soft-gluon approximation for real corrections.

Speaker: Marco Bonetti (Karlsruhe Institute of Technology (KIT))

Bonetti_QCDatLHC18.pdf

17:16 Production of Higgs bosons with large transverse momentum

In this talk I will present our results on the Higgs plus jet production at the large transverse momentum, that is, above the top mass threshold. In particular, it will be shown how corresponding two-loop amplitudes were computed in approximation of nearly massless top quarks.

Speaker: Kirill Kudashkin (Karlsruhe Institute of Technology (KIT))

QCD_LHC2018kudashkin_presentation.pdf

17:39 Role of the Z polarization in the H > bb measurement.

In this talk I show that the $Z$ boson polarization has relevant information to distinguish the signal $pp \to ZH$, $H \to b\bar{b}$ from the dominant background $Zb\bar{b}$, which is part of the $\mathcal{O}(\alpha_s^2)$ correction to the Drell-Yan $Z$ production, and can help us to finally observe the largest Higgs boson branching ratio.

Speaker: Junya Nakamura (Universität Tübingen)

z_pol-nakamura.pdf

16:30 → 18:00 Monte Carlo and resummation: Joint with PDFs, 𝛼ₛ and soft QCD

Conveners: Josh McFayden (CERN), S. Moch (UHH), Simon Platzer (University of Vienna (AT)), Stefano Camarda (Johannes Gutenberg Universitaet Mainz (DE)), Steffen Schumann (Georg-August-Universitaet Goettingen)

16:30 Effects of parton shower and underlying event modelling in Higgs measurements and searches

A number of Higgs measurements and searches for new phenomena in the Higgs sector rely on identification or vetos of particle jets with fairly low transverse momentum in the range of 20-30 GeV. In these cases uncertainties from the modelling of the parton shower and the underlying event can be sizeable. This talk will give an overview of how these uncertainties enter in several analyses.

Speaker: Mario Jose Sousa (Shandong University (CN))

QCDatLHC2018_MarioSousa.pdf

16:50 MC tunes for Run 2 of the LHC and beyond (HL-LHC)

Abstract will be available shortly. The talk has been suggested by the organizer
ATLAS + CMS.
The content of this talk is related to the activities of one the CMS groups (Generator, Forward, SM, Top) and ATLAS groups (PMG, SM, TOP, Forward).

Speaker: Thorsten Kuhl (Deutsches Elektronen-Synchrotron (DE))

20180827QCDatLHC2018.pdf

16:30 → 18:00 Perturbative QCD, jets and substructure

16:30 Precise predictions for diboson processes

I will review recent theory developments for diboson production at the LHC within the puclicly available code MATRIX: With the two lepton plus two neutrino channels, which mix ZZ and WW production, NNLO corrections have been completed to all experimentally relevant leptonic final states for diboson processes. NLO corrections to the loop-induced gg channel are formally of N3LO accuracy, but constitute an important contribution to the (fiducial) diboson rates in certain cases. Finally, the inclusion of NNLO accuracy in fully flexible hadron level events (NNLOPS) was recently achieved for a diboson process, namely WW production, which will be discussed in detail.

Speaker: Marius Wiesemann (CERN)

Wiesemann_QCDatLHC_2018.pdf

17:00 Tests of the Gauge Structure of the Electroweak Sector with ATLAS

Measurements of the cross sections of the production of two or three 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. Such studies can be complemented by measurements of vector boson fusion or vector boson scattering processes with one or two gauge boson in association with two jets at high invariant mass, respectively. The ATLAS collaboration has performed detailed measurements of integrated and/or differential cross sections of the such processes at centre-of-mass energies of 8 and 13 TeV. In this talk, we will highlight the most recent results available, also focusing on the QCD modelling aspects of the measurements.

Speaker: Jonathan Crane (University of Manchester (GB))

QCD@LHC_2018_JonathanCrane.pdf

17:30 Prospects for a measurement of the W boson mass in the all-jets final state at hadron colliders

Precise measurements of the mass of the W boson are important to test the overall consistency of the Standard Model of particle physics. The current best measurements of the W boson mass come from single production measurements at hadron colliders in its decay mode to a lepton (electron or muon) and a neutrino and pair production of W bosons at lepton colliders, where also the decay mode of the W boson to a quark anti-quark pair has been considered. In this study, prospects for a measurement of the W boson mass in the all-jets final state at hadron colliders are presented. Compared to other methods for measuring the W mass, a measurement in the all-jets final state would be complementary in methodology and have systematic uncertainties orthogonal to previous measurements. We have estimated the main experimental and theoretical uncertainties affecting a measurement in the all-jets final state making use of jet substructure techniques.

Speaker: Andreas Hinzmann (Hamburg University (DE))

180827 - W mass all-jets.pptx.pdf

18:00 → 19:00 Welcome Reception

Tuesday, 28 August

09:00 → 11:00 Plenary

Convener: Daniel Maitre

09:00 Joint TH+EXP: QCD background processes in BSM searches (60' + 15')

Speakers: Jonas Lindert (University of Durham (GB)), Paolo Gunnellini (University of Hamburg)

QCDatLHC_Gunnellini_Lindert.pdf

10:15 QCD corrections for BSM signal processes (35' + 10')

Speaker: Anna Kulesza (University of Muenster)

QCDBSM18_v4.pdf

11:00 → 11:30 Coffee break

11:30 → 13:00 Plenary

Convener: Markus Diehl (DESY)

11:30 Recent results in Higgs and BSM searches at CMS (35' + 10')

Speaker: Dezso Horvath (Wigner RCP, Budapest (HU))

higgs-susy-cms_2018aug.pdf

12:15 QCD measurements with Heavy Ions (35' + 10')

Speaker: Livio Bianchi (Universita e INFN Torino (IT))

LivioBianchi_QCD@LHC2018_v2.pdf

13:00 → 14:30 Lunch

14:30 → 16:00 EW, Higgs and BSM

14:30 Measurements of the Higgs boson properties at the ATLAS experiment

After the discovery of the Higgs boson in summer 2012, the understanding its properties has been a high priority of the ATLAS physics program. Measurements of Higgs boson properties sensitive to its production processes, decay modes, kinematics, mass, and spin/CP properties based on pp collision data recorded at 13 TeV are presented. The analyses in several decay channels will be described and the results of the combination of different decay channels will be shown.

Speaker: Paul Glaysher (DESY)

QCD@LHC.pdf

14:53 Theory input for VBS

In this talk, I review recent theoretical developments for VBS processes at the LHC.

Speaker: Mathieu Pellen (University Wuerzburg)

PELLEN_Dresden_VBS_2018.pdf

15:16 Latest results on VBF and VBS processes at CMS

This talk describe recent results on the measurement of the Electroweak production of V and VV + jets.

Speaker: Jakob Salfeld-Nebgen (Princeton University (US))

QCDatLHCv5_JS.pdf

15:39 New Results on Vector Boson Scattering Processes with the ATLAS Detector

New Results on Vector Boson Scattering Processes with the ATLAS Detector

Measurements of the cross sections of the vector-boson scattering processes 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 observed the electroweak production of WZ and same-signed WW pairs in vector boson scattering processes at a center of mass energy of 13 TeV using the 2015+2016 data-sets. We present the corresponding analyses in detail and discuss the compatibility to theory predictions.

Speaker: Wenhao Xu (University of Michigan (US))

Wenhao Xu - QCD@LHC 2018.pdf

14:30 → 16:00 Monte Carlo and resummation

14:30 Beyond NLL

Speaker: Frederic Alexandre Dreyer (MIT)

talk_qcdlhc18.pdf

14:52 Direct space resummation for Higgs and Drell-Yan at N3LL

We present a direct space resummation formalism for colour singlet production in hadronic collisions. We focus on N3LL results for Higgs boson production in gluon-gluon fusion as well as results for Drell-Yan production, we show predictions with phenomenological cuts matched to NNLO fixed-order predictions.

Speaker: Mr Wojciech Bizon (University of Oxford (GB))

wbizon-dresden.pdf

15:14 High-energy resummation for the background to weak boson fusion

The weak boson fusion contribution to Higgs boson production is enhanced significantly by requiring a large invariant mass and rapidity separation between the associated jets. This induces large logarithmic corrections in the prediction for the gluon-fusion background, which are incorporated to all orders within the High Energy Jets (HEJ) formalism. We present HEJ predictions for the gluon-fusion production of a Higgs boson in association with at least two jets, matched to fixed-order predictions at leading and next-to-leading order and including corrections due to finite top and bottom quark masses.

Speaker: Andreas Maier (Durham University)

QCDatLHC_2018.pdf

15:36 Higgs

Speaker: Simone Marzani (Università di Genova and INFN Genova)

marzani_QCD18_higgs.pdf

14:30 → 16:00 PDFs, 𝛼ₛ and soft QCD

14:30 Determination of the strong coupling constant alphas(MZ) in next-to-next-to-leading order QCD using H1 jet cross section measurements

The strong coupling constant $\alpha_s$ is determined from inclusive jet and dijet cross sections in neutral-current deep-inelastic ep scattering (DIS) measured at HERA by the H1 collaboration using next-to-next-to-leading order (NNLO) QCD predictions. The dependence of the NNLO predictions and of the resulting value of $\alpha_s(m_Z)$ at the $Z$-boson mass $m_Z$ are studied as a function of the choice of the renormalisation and factorisation scales. Using inclusive jet and dijet data together, the strong coupling constant is determined to be $\alpha_s(m_Z) = 0.1157\,(20)_{exp}\,(29)_{th}$. Complementary, $\alpha_s(m_Z)$ is determined together with parton distribution functions of the proton (PDFs) from jet and inclusive DIS data measured by the H1 experiment. The value $\alpha_s(m_Z) = 0.1142\, (28)_{tot}$ obtained is consistent with the determination from jet data alone. The impact of the jet data on the PDFs is studied. The running of the strong coupling is tested at different values of the renormalisation scale and the results are found to be in agreement with expectations.

Eur.Phys.J.C77 (2017), 791 [arxiv:1709.07251]

Speaker: Daniel Britzger (Ruprecht Karls Universitaet Heidelberg (DE))

180828-britzger-alpha_s.pdf

14:55 Strong coupling constant extraction from high-multiplicity Z+jets observables

I will present a strong coupling constant extraction at next-to-leading order QCD accuracy using ATLAS Z+2,3,4 jets data. This is the first extraction using processes with a dependency on high powers of the coupling constant. The values of the strong coupling constant at the Z mass obtained are compatible with the world average and with uncertainties commensurate with other next-to-leading order extractions at hadron colliders.

Speaker: Daniel Maitre

QCDatLHC_maitre.pdf

15:15 Determination of $\alpha_s(m_Z)$ from a fit of the Z-boson transverse momentum distribution measured by CDF to NNLO+NNLL predictions

The strong-coupling constant $\alpha_s(m_Z)$ is measured from the transverse momentum distribution of Z bosons measured at $\sqrt{s} = 1.96$ TeV with the CDF experiment, using predictions based on qt resummation at NNLO+NNLL, as implemented in the DYTURBO program. The measurement is performed through a simultaneous fit of $\alpha_s(m_Z)$, PDFs, and the non-perturbative Sudakov form factor.

Speaker: Stefano Camarda (Johannes Gutenberg Universitaet Mainz (DE))

zptalphas.pdf

15:35 Determination of the strong coupling constant from inclusive jet cross section data from multiple experiments

https://arxiv.org/abs/1712.00480

Speaker: Daniel Savoiu (KIT - Karlsruhe Institute of Technology (DE))

QCDLHC_talk_alpha_s_2018-08-28_final.pdf

14:30 → 16:00 Perturbative QCD, jets and substructure

14:30 Two-loop five-gluon helicity amplitudes in QCD via integrand reduction

I will present a calculation of the leading-colour five-gluon amplitude at two loop in QCD. The calculation is performed by means of D-dimensional integrand reduction method, complemented with the finite-field reconstruction techniques and momentum twistor parameterization. Numerical results for all helicity configurations are obtained by employing both sector decomposition methods and IBP reduction to master integrals.

Speaker: Heribertus Bayu Hartanto (Durham University)

Bayu_QCDatLHC2018.pdf

15:00 Jet(s) with the CoLoRFulNNLO framework

We observe more and more advances in the technology of multiloop calculations.
Hence it is of utmost importance to develope computational frameworks which
can tackle the computational burden presented by the regularization
of up to two unresolved parton emissions coming from the matrix elements.
CoLoRFulNNLO is such a framework built around local subtractions
derived from first principles. In my talk I give a detailed overview of the
framework with special emphasis on its application to LHC processes involving
jet production.

Speaker: Adam Kardos (University of Debrecen)

kardos.pdf

15:30 Differential jet cross sections at the CMS experiment

We present measurements of differential jet cross sections over a wide range in transverse momenta from inclusive jets to multi-jet final states. Studies on the impact that these measurements have on the determination of the strong coupling alpha_s as well as on parton density functions are reported.

Speaker: Mr Suman Chatterjee (Tata Inst. of Fundamental Research (IN))

Jet_Talk_Suman.pdf

16:00 → 16:30 Coffee break

16:30 → 18:00 EW, Higgs and BSM

16:30 Recent HH Results at CMS

The production of Higgs boson pairs (HH) offers a unique opportunity to explore the structure of the Higgs field potential through the determination of the Higgs boson self interaction. Despite being an extremely rare process, with a predicted cross section of about 33 fb at a center-of-mass energy of 13 TeV, variations of the Higgs couplings, or the presence of heavy resonances, might enhance the production rate and hence reveal the presence of physics beyond the Standard Model. The most recent results on searches for double Higgs production, obtained from the CMS Collaboration with data collected at sqrt(s) = 13 TeV, are here presented, with focus on the different decay channels explored and their combination.

Speaker: Francesco Brivio (Universita & INFN, Milano-Bicocca (IT))

FBrivio_HH_CMS.pdf

16:53 NLO corrections to Higgs boson pair production in a non-linear EFT

-

Speaker: Ludovic Michel Scyboz (Max-Planck-Institut fur Physik (DE))

scyboz_QCDAtLHC.pdf

17:16 Searches for non-SM Higgs bosons and for BSM decays of the Higgs boson at the ATLAS experiment

Several theories beyond the Standard Model predict the existence of additional neutral or charged Higgs particles, as well as decays of the Higgs boson that are either forbidden or strongly suppressed in the SM.Results from selected recent searches for additional Higgs bosons in different production processes and decay modes, and for BSM decays of the 125 GeV-Higgs boson will be presented.

Speaker: Pawel Jan Klimek (Northern Illinois University (US))

PawelKlimek_HBSM_ATLAS.pdf

17:39 QCD Issues in Searches for New Physics with the ATLAS Detector

QCD Issues in Searches for New Physics with the ATLAS Detector

The ATLAS experiment at the LHC has a broad search program covering a wide variety of models of physics beyond the Standard Model, from simplified models to UV complete models like supersymmetry. In many searches, the final states include one or more hadronic object, and QCD constitutes a crucial background, the control and understanding of which is critical for sensitivity to new physics.  Searches make use of QCD scaling rules for background estimation, jet sub-structure for signal and background separation, and higher-order calculations and resummation for signal cross-sections.  Additional complex QCD issues arise in searches for R-hadrons — hadrons that include long-lived supersymmetric particles — or other new colored particles.  This talk summarizes recent search results from the ATLAS experiment, highlighting techniques and issues that most strongly interact with QCD.

Speaker: Matthias Saimpert (Deutsches Elektronen-Synchrotron (DE))

qcdatlhc_28082018.pdf

16:30 → 18:00 Heavy Quarks

16:30 Top-quark pair production beyond NNLO

The total top-antitop production cross section at hadron colliders is
one of the key observables of the Standard Model. Comparisons of LHC
measurements with theoretical calculations are being used to determine
the top-quark mass and the strong coupling and are included in global
PDF fits. These applications are currently based on calculations at
the next-to-next-to-leading order (NNLO) in QCD supplemented by
soft-gluon resummation at the next-to-next-to-leading logarithmic
order. In this talk I will present recent developments in computing
the cross section beyond NNLO, which is necessary to keep up with the
ever increasing experimental accuracy.

Speaker: Jan Piclum (University of Siegen)

piclum.pdf

17:00 Top quark properties and mass measurements with the ATLAS detector

The top quark is unique among the known quarks in that it decays before it has an opportunity to form hadronic bound states. This makes measurements of its properties particularly interesting as one can access directly the properties of a bare quark. The latest measurements of these properties with the ATLAS detector at the LHC are presented using 8 TeV and 13 TeV data. Limits on the rate of flavour changing neutral currents in the production or decay of the top quark are also reported. The production of top-quark pairs in association with W and Z bosons and with photons are also presented. These process are all compared to the best available theoretical calculations. The latest ATLAS measurements of the top quark mass in lepton+jets, dilepton, and all-hadronic final states are also reported. In addition, measurements aiming to measure the mass in a well-defined scheme are presented.

Speaker: Kevin De Vasconcelos Corga (Centre National de la Recherche Scientifique (FR))

document.pdf

17:30 Hard Photons in Hadroproduction of Top Quarks with Realistic Final States

We present a complete description of top quark pair production in association with a hard photon in the dilepton channel. Our calculation is accurate to NLO in QCD. It is based on matrix elements for e+νeμ−ν¯μbb¯γ production and includes all resonant and non-resonant diagrams, interferences, and off-shell effects of the top quarks and the W gauge bosons. This calculation constitutes the first full computation for top quark pair production with a final state photon in hadronic collisions at NLO in QCD. Numerical results for total and differential cross sections are presented for the LHC at a centre-of-mass energy of s√=13 TeV. For some new physics observables we observe shape distortions of more than 100%. In addition, we confirm that the size of the top quark off-shell effects for the total cross section is consistent with the expected uncertainties of the narrow-width-approximation. Triggered by ongoing experimental analyses, we also report on the cross section ratio to the pp→e+νeμ−ν¯μbb¯ process. Not only is the ratio more stable against radiative corrections but it also has reduced scale dependence as compared to the pp→e+νeμ−ν¯μbb¯γ cross section alone. Thus, it represents an interesting observable to probe new physics at the LHC.

Speaker: Torsten Weber (RWTH Aachen University)

talk.pdf

16:30 → 18:00 Monte Carlo and resummation

16:30 Colour Matrix Element Corrections

Speaker: Malin Sjodahl (Lund University)

QCDatLHCMalinSjodahl1808.pdf

16:52 Soft Gluon Evolution and Colour Reconnection

We consider soft gluon evolution of a system of clusters forming the initial state of the cluster hadronziation model, in order to constrain colour reconnection models from a perturbative point of view.
We show that this ansatz produces clusters with properties attributed to
a colour pre-confined state and find strong evidence for formerly investigated colour reconnection models based on geometric properties.
We also explore the possibility of colour flows giving rise to
baryonic clusters and propose a simple parametrization to incorporate the
effects of soft gluon evolution in a full monte carlo event generator.

Speaker: Patrick Kirchgaesser

QCDatLHC2018_Dresden.pdf

17:14 Using Pseudo-Dipoles for Resonance-Aware NLO-Subtraction

NLO-subtraction schemes such as CS-dipole-subtraction are indispensable for MC-Generators to calculate real and virtual corrections efficiently. However, those algorithms suffer from numerical inefficiencies and even cause distortions in physical distributions when interfaced with parton showers, if the process in question comprises potentially resonant particles.
In this talk I will elucidate this matter and offer an alternative subtraction-scheme, which makes use of so called pseudo-dipoles. I will show results, which have been calculated with a SHERPA-implementation of this new pseudo-dipole-subtraction and compare them to the ones obtained with ordinary CS-dipole-subtraction.

Speaker: Sebastian Liebschner (IKTP Dresden)

QCDatLHC.pdf

17:36 Next-to-leading power correction in particle scattering near threshold

I will discuss recent developments in the calculation of next-to-leading power corrections in Drell Yan and other electroweak annihilation processes.

Speaker: Dr Leonardo Vernazza (Nikhef and University of Amsterdam)

QCD@LHC-2018.pdf

16:30 → 18:00 Perturbative QCD, jets and substructure

16:30 N3LO QCD DIS Single-jet production and NNLO QCD e^+e^- event orientation with NNLOJET

In this talk, recent results on the calculation of fully differential single-jet production in neutral current deep inelastic scattering at next-to-next-to-next-to leading order (N3LO) in the strong coupling are presented. The results are obtained by the combination of antenna subtraction at next-to-next-to leading order (NNLO) with the method of projection to born. Details of the combination of the two approaches will be discussed. Phenomenological results on NNLO QCD predictions for event-orientations in e^+e^- - annihilation will be also shown.

Speaker: Jan Niehues

DresdenNiehues.pdf

17:00 Groomed jet substructure observables for inclusive jet production

The phenomenology of highly energetic jets and their substructure plays an important role for the physics program at the LHC. In recent years various grooming techniques have been proposed that need to be included consistently in perturbative calculations. Within Soft Collinear Effective Theory (SCET) we establish factorization theorems for jet substructure observables measured on an inclusive jet sample. The developed effective field theory framework allows the resummation of large logarithmic corrections to next-to-leading logarithmic (NLL) accuracy and a consistent treatment of non-perturbative effects. For example, we consider the jet mass distribution with and without grooming. We present numerical results and compare to the available data from the LHC.

Speaker: Felix Ringer (Lawrence Berkeley National Laboratory)

QCD@LHC_FRinger.pdf

17:30 Jet energy scale and jet substructure performance in CMS

Jets are the experimental signature of energetic quarks and gluons produced in high energy processes. A detailed understanding of both the energy scale and the transverse momentum resolution of jets is of crucial importance for the analysis of perturbative QCD processes. In addition, the substructure, shape and mass of jets is an important tool to separate and study quark and gluon initiated jets as well as jets initiated by highly boosted W, Z, Higgs bosons and top quarks decaying to quarks. In this talk, we present the measurements of CMS jet energy scale and resolution, as well as the performance of jet substructure tagging algorithms using the data sample collected in proton-proton collisions at a center-of-mass energy of 13 TeV.

Speaker: Robin Cameron Aggleton (Hamburg University (DE))

jec_qcdlhc_dresden_18_16to9.pdf

Wednesday, 29 August

09:00 → 11:00 Plenary

Convener: Eram Syed Rizvi (Queen Mary, University of London)

09:00 Uncertainties and challenges in jet reconstruction in ATLAS (35' + 10')

Speaker: Aparajita Dattagupta (University of Oregon (US))

Uncertainties_Challenges_JetReco_QCDatLHC_29thAug18.pdf

09:45 Joint TH+EXP: Inclusive and dijet production at the LHC (60' + 15')

Speakers: Bogdan Malaescu (Centre National de la Recherche Scientifique (FR) & CERN), Joao Pires

pires.pdf

QCDatLHC_Malaescu.pdf

11:00 → 11:30 Coffee break

11:30 → 13:00 Plenary

Convener: Andreas Maier (Durham University)

11:30 Progress in multiloop and multileg calculations (35' + 10')

Speaker: Stephen Jones (MPI, Munich)

sjones_qcdatlhc2018.pdf

12:15 EW corrections in the light of QCD precision (35' + 10')

Speaker: Marek Schoenherr (CERN)

QCDatLHC_MarekSchoenherr.pdf

13:00 → 14:30 Lunch

15:00 → 18:00 Excursion

A boat trip from Dresden downtown to Pillnitz Castle with time to spend in the gardens and vineyards around the castle.

18:15 → 18:35 Bus to conference dinner

19:00 → 00:00 Conference Dinner

Thursday, 30 August

09:45 → 11:00 Plenary

Convener: Steffen Schumann (Georg-August-Universitaet Goettingen)

09:45 Joint TH+EXP: Jet substructure and H/V/top-tagging (60' + 15')

Speakers: Danilo Enoque Ferreira De Lima (Ruprecht Karls Universitaet Heidelberg (DE)), Dr Simone Marzani (Università di Genova and INFN Genova)

qcdatlhc-2018.pdf

11:00 → 11:30 Coffee break

11:30 → 13:00 Plenary

Convener: Gunnar Bali (Universität Regensburg)

11:30 Heavy flavour production processes (35' + 10')

Speaker: Stefano Forte (Università degli Studi e INFN Milano (IT))

dresden18.pdf

12:15 Heavy flavour production and decay with LHCb (35' + 10')

Speaker: Nicola Anne Skidmore (Ruprecht Karls Universitaet Heidelberg (DE))

QCDatLHCb.pdf

13:00 → 14:30 Lunch

14:30 → 16:00 Heavy Quarks

14:30 Flavour Anomalies in Rare Decays at LHCb

Rare decays are powerful probes for Physics beyond the Standard Model
(SM), as new particles can have a large impact on physics observables.
Recent results on lepton universality tests and measurements of
branching fractions and angular distributions of rare b->sll decays have
shown tensions with the SM predictions. The LHCb experiment is ideally
suited for the study of the these flavour anomalies, due to its large
acceptance, precise vertexing and powerful particle identification
capabilities. The latest results from LHCb on the flavour anomalies will
be presented and their interpretation will be discussed.

Speaker: Christoph Michael Langenbruch (Rheinisch Westfaelische Tech. Hoch. (DE))

langenbruch.pdf

15:00 Long-distance effects in B->K(*) l+ l-

I will discuss recent developments regarding long-distance effects in B->K()l+ l- decays.
Precise knowledge of these effects is needed for the interpretation of the present anomaly seen in the experimental results. The approach I discuss relies on the analytic properties of the hadronic matrix elements. It combines the available theory information beyond the physical phase space with experimental data of hadronic decays B->K() psi. The results are predictions for the rare decay within the Standard Model and beyond.

Speaker: Danny van Dyk (TU München)

talk.pdf

15:30 CP Violation in pure hadronic three-body B meson decays

The search for CP violation is a large part of the flavour programs at LHCb and the B factories, with pure hadronic decays as the key players. Three-body decays, which form a large part of the B meson branching fraction, contain much more information than two-body decays, because of their non-trivial kinematic structure. Recently, these decays were described using a QCD factorization framework similar to two-body decays, but with new non-perturbative inputs. I discuss a first study of CP violation in three-body B decays using this new framework.

Speaker: Dr Keri Vos (Siegen University)

ThreebodyQCD@LHC.pdf

14:30 → 16:00 Monte Carlo and resummation

14:30 Shower Variations and Tuning

Speaker: Andrzej Konrad Siodmok (Polish Academy of Sciences (PL))

Siodmok_Shower_Variations _and_Tuning.pdf

14:52 Parton Shower Cutoff and the Heavy Quark Mass Parameter

Speaker: Andre Hoang (University of Vienna)

Hoang-Topmass-Parallel.pdf

15:14 PS vs Resummation

Speaker: Daniel Reichelt (Technische Universitaet Dresden (DE))

QCDatLHC_DReichelt.pdf

15:36 Matching and merging with massive $b$-quarks

We present a new algorithm to incorporate calculations with massive $b$-quarks, usually performed in the four flavour scheme, into a merged simulation obtained in the five flavour scheme. We apply this algorithm to $tt+\mathrm{jets}$ / $ttbb$ production, study the uncertainties of this newly developed method and compare our results to dedicated 4F/5F simulations.

Speaker: Johannes Krause (TU Dresden)

QCD_LHC_johannes_krause.pdf

14:30 → 16:00 PDFs, 𝛼ₛ and soft QCD

14:30 Parton distributions from the collider data

Results of the QCD analysis of a variety of the hard-scattering data is overviewed with a particular focus on determination of the quark distributions in the nucleon. A potential of the recent precise data collected at the LHC for the problem of parton species disentangling is discussed and compared to the impact of the low-energy fixed-target data. Finally, remaining challenges and potential improvements in the field are outlined.

Speaker: Serguei Alekhin (State Res.Center of Russian Feder. Inst.f.High Energy Phys. (IFVE))

15:00 Drell-Yan measurements and PDFs

The talk should cover W, Z/gamma* measurements sensitive to PDFs, as well as measurements of EW observables which are affected by significant PDF uncertainties (sin2thetaW, W mass).

Speaker: Eram Syed Rizvi (Queen Mary, University of London)

QCD@LHC-2018.pdf

15:30 Top quark and jets measurements sensitive to PDFs

The talk will cover measurements and QCD analyses of inclusive and differential
top quark pairs and single top production, and of jets production, from ATLAS, CMS and LHCb.

Speaker: Suman Chatterjee (Tata Inst. of Fundamental Research (IN))

PDFTalk_Dresden.pdf

14:30 → 16:00 Perturbative QCD, jets and substructure

14:30 The Lund Jet Plane

Lund diagrams, a representation of the phase space within jets, have long been used in discussing parton showers and resummations. I will point out that they can also serve as a powerful tool for experimentally characterising the radiation pattern within jets. I will briefly comment on some of their analytical properties and highlight their scope for constraining Monte Carlo simulations. I will examine the use of the Lund plane for boosted electroweak boson tagging, which when used as an input to deep-learning methods yields high performance. Furthermore, much of that performance can be reproduced by using the Lund plane as an input to simpler log-likelihood type discriminators. This suggests a potential for unique insight and experimental validation of the features being used by machine-learning approaches. In the context of this discussion, I will also highlight the importance of accounting for detector effects when considering the performance of machine-learning approaches.

Speaker: Frederic Alexandre Dreyer (MIT)

talk_qcdlhc18.pdf

15:00 Tests of Perturbative QCD with Photon Final States at the ATLAS Experiment

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 numerous cross section measurements of prompt photon production, among which are a precise measurement of the production of isolated prompt photons in association with heavy flavor jets and a first measurement of the production cross-section of tri-photon final states at a center of mass energy of 8 TeV, as well as a photon plus jet cross section measurement at 13 TeV. If available, a measurement of diphotons in association with jets and a ratio of photon cross sections between 8 and 13 TeV will also be presented. The results are compared with state-of-the-art theory predictions, indicating several interesting discrepancies.

Speaker: Ana Rosario Cueto Gomez (Universidad Autonoma de Madrid (ES))

ProbesQCDPhotons.pdf

15:30 New Results on Z Boson Production with the ATLAS Detector

Precision measurements of the Drell-Yan production of 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.
ATLAS performed a measurement of the effective leptonic weak mixing angle using electron and muon pairs from Z boson decay at a center of mass energy of 8 TeV. It consists of a set of measurements of the angular coefficient most sensitive to the weak mixing angle, binned in dilepton mass and rapidity reducing PDF uncertainties on the measurement.
In order to test the electroweak sector with single Z boson final states, ATLAS has published a first measurement of the tau-polarization in Z events as well as the cross-section of the electroweak production of Z bosons at 13 TeV. These results will be presented and discussed.

Speaker: Peter Wagner (University of Bonn (DE))

wagner_qcdatlhc2018.pdf

16:00 → 16:30 Coffee break

16:30 → 18:00 Heavy Quarks

16:30 Combination and QCD analysis of beauty and charm production cross section measurements in deep inelastic ep scattering at HERA

Measurements of open charm and beauty production cross sections in deep inelastic $ep$ scattering at HERA from the H1 and ZEUS Collaborations are combined. Reduced cross sections are obtained in the kinematic range of negative four-momentum transfer squared of the photon $2.5$~GeV$^2\le Q^2 \le 2000$ GeV$^2$ and Bjorken scaling variable $3 \cdot 10^{-5} \le x_{\rm Bj} \le 5 \cdot 10^{-2}$. The combination method accounts for the correlations of the statistical and systematic uncertainties among the different datasets. Perturbative QCD calculations are compared to the combined data. A next-to-leading order QCD analysis is performed using these data together with the combined inclusive deep inelastic scattering cross sections from HERA. The running charm- and beauty-quark masses are determined as $m_c(m_c) = 1.290^{+0.046}_{-0.041} {\rm (exp/fit)}$ ${}^{+0.062}_{-0.014} {\rm (model)}$ ${}^{+0.003}_{-0.031} {\rm (parameterisation)}$ GeV and $m_b(m_b) = 4.049^{+0.104}_{-0.109} {\rm (exp/fit)}$ ${}^{+0.090}_{-0.032} {\rm (model)}$ ${}^{+0.001}_{-0.031} {\rm (parameterisation)}$ GeV.

arxiv:1804.01019, accepted by EPJC.

qcdATlhc2018.pdf

17:00 Three loop QCD corrections to heavy quark form factors

We present color planar and complete light quark QCD contributions to the three loop heavy quark form factors in the case of vector, axialvector, scalar and pseudoscalar currents. We evaluate the master integrals applying a new method based on differential equations for general bases, which is applicable for all first order factorizing systems. The analytic results are expressed in terms of harmonic polylogarithms and real-valued cyclotomic harmonic polylogarithms.

Speaker: Dr Narayan Rana (DESY)

RanaQCDLHC18.pdf

17:30 Exotic and Conventional Quarkonium Physics Prospects at Belle II

The Belle II experiment, now operating at the KEK laboratory in Japan, is a substantial upgrade of both the Belle detector and the KEKB $e^+ e^-$accelerator. It aims to collect 50 times more data than existing B-Factory samples. Belle II is uniquely capable to study the so-called "XYZ" particles: heavy exotic hadrons consisting of more than three quarks. First discovered by Belle, these now number in the dozens, and represent the emergence of a new category within quantum chromodynamics. This talk will present the capabilities of Belle II to explore both exotic and conventional quarkonium physics.

Speaker: Bianca Scavino (Uni Mainz)

Scavino_Dresden.pdf

16:30 → 18:00 Monte Carlo and resummation

16:30 Massive bottom quark effect in Drell-Yan P_T spectrum

We study the transverse momentum spectrum for Drell-Yan production including the bottom mass effect. The pt-distribution of DY or Z boson is very important observable at the LHC, particularly to the ratio of W boson and Z boson spectrum to precisely measure of the W boson mass. The presence of an extra mass scale namely the bottom mass along with the hard scale and the pt-scale makes it very difficult to study within QCD. The three different mass scales give rise to several mass hierarchies leading to large logarithms which needs to be resummed at all orders to get a meaningful result. Moreover the different regions have to be properly matched to get a smooth distribution avoiding double counting or gaps. For these kind of problem, effective theories show a better grasp onto the problem. Using SCET based factorisation we resum these large logarithms in a systematic way upto NNLLp accuracy. We discuss different theoretical issues namely order counting, rapidity divergences etc. We identify two different kind of contributions namely the primary effect where bottom quark initiates the hard process and the secondary effect where bottom quark contributes through loop. Both these contributions are included into our calculation. Finally we present properly matched pt distribution which will be useful at the LHC to the measurement of Z boson and W boson properties.

Speaker: Das Goutam (DESY Hamburg)

GD_qcdatlhc.pdf

16:52 Non-global Logarithms beyond Leading Colour

Speaker: Matthew DeAngelis

QCDatLHC_DeAngelis.pdf

17:14 Automated calculation of two-loop soft functions in SCET

Perturbative calculations for many collider observables suffer from large logarithmic corrections associated with soft emissions or radiation collinear to beam or jet directions. Resummation using SCET techniques is based on factorisation theorems, and requires the calculation of jet, soft and beam functions to some perturbative accuracy. This task has up to now mainly been achieved analytically, on a case-by-case basis.

To facilitate the resummation of global logarithms to NNLL accuracy, we present a framework to numerically compute the two-loop soft function for a general class of observables containing e.g. e+e-event shapes and inclusive hadron collider observables. The algorithm has been implemented in the publicly available program SoftSERVE, and is currently limited to processes with two hard (coloured) directions. I will present the general strategy of our approach, some new results for event-shape and jet-grooming observables, as well as recent progress on extending the setup to processes with more than two jet-like directions.

Speaker: Rudi Rahn (University of Bern)

Rahn_QCDatLHC.pdf

17:36 Resummation of Non-global Logarithms in Effective Field Theory

Starting from a factorization theorem in effective field theory, we derive a parton-shower equation for the resummation of non-global logarithms. We have implemented this shower and interfaced it with a tree-level event generator to obtain an automated framework to resum the leading logarithm of non-global observables in the large-Nc limit. Using this setup, we compute gap fractions for dijet processes and isolation cone cross sections relevant for photon production. We compare our results with fixed-order computations and LHC measurements. We find that naive exponentiation is often not adequate, especially when the vetoed region is small since non-global contributions are enhanced due to their dependence on the veto-region size.

Speaker: Dr Dingyu Shao (CERN)

QCD@LHC2018_shao.pdf

16:30 → 18:00 PDFs, 𝛼ₛ and soft QCD

16:30 Moments of PDFs from Lattice QCD

Mellin moments of PDFs are calculable as expectation values of local operators within external states, using Lattice QCD. With sufficiently small statistical and systematic uncertainties, these provide information that will be complementary to parametrizations obtained from global fits to experimental data. I will present such lattice results.

Speaker: Prof. Gunnar Bali (Universität Regensburg)

balitalk.pdf

17:00 A determination of the strong coupling constant from a global QCD analysis

I present the recent determination of αs performed by the NNPDF collaboration. I particularly discuss the novel methodology adopted in the fit, as well as the breakdown of the uncertainties.

Speaker: Zahari Dimitrov Kassabov Zaharieva (University of Cambridge (GB))

talk.pdf

17:30 Recent developments in the CTEQ-TEA global analysis

We will talk about the recent progress in the CTEQ-TEA global analysis.

Speaker: Dr Tie-Jiun Hou (Xinjiang University)

2018.0830.QCDatLHC.TJHou.pdf

16:30 → 18:00 Perturbative QCD, jets and substructure

16:30 Precision determination of the Wtb coupling in single top production

We present our calculation of next-to-leading order QCD effects in single top production for a precision determination of the Wtb coupling. The calculation is performed analytically with an off-shell top quark and includes relevant operators from the Standard Model Effective Field Theory (SMEFT) that modify the Wtb coupling also at next-to-leading order in QCD. We discuss the phenomenological importance and put our calculation into the context of current studies.

Speaker: Tobias Neumann (Illinois Tech / Fermi National Accelerator Laboratory)

qcdlhc.pdf

17:00 Renomalization of QCD at four and five loops

We present an overview of the current status of calculations for the QCD renormalization constants.

Speaker: Peter Marquard (DESY)

Friday, 31 August

09:00 → 11:00 Plenary

Convener: Dominik Stoeckinger (TU Dresden)

09:00 Joint TH+EXP: Pileup modelling and mitigation at the LHC (60' + 15')

Speakers: Matteo Cacciari (LPTHE Jussieu), Satoshi Hasegawa (Fermi National Accelerator Lab. (US))

Satoshi_and_Matteo__Pileup_QCDatLHC2018.pdf

10:15 Recent developments in resummation (35' + 10')

Speaker: Luca Rottoli (University of Oxford)

rottoli_resum_Dresden2018.pdf

11:00 → 11:30 Coffee break

11:30 → 13:05 Plenary

Convener: Adam Kardos (University of Debrecen)

11:30 Recent developments in Monte Carlo event generators (35' + 10')

Speaker: Silvan Kuttimalai (SLAC)

qcdatlhc-18-kuttimalai.pdf

12:15 Vector boson(s) and jet production in ATLAS (35' + 10')

Speaker: Arantxa Ruiz Martinez (Univ. of Valencia and CSIC (ES))

ARuiz_QCDatLHC2018.pdf

13:00 Farewell

QCD@LHC 2018 Farewell.pdf

13:05 → 14:30 Lunch