QCD@LHC 2019

Ciaran Williams (SUNY Buffalo), Doreen Wackeroth (University at Buffalo, SUNY), Salvatore Rappoccio (Buffalo)

This is the 10th 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
  • Abhijith Gandrakota
  • Alessandro Tricoli
  • Alessandro Vicini
  • Alexander Huss
  • Anastasia Karavdina
  • Andrea Pelloni
  • Andrzej Siodmok
  • Andy Buckley
  • Antonio Sbrizzi
  • Ashley Parker
  • Avto Kharchilava
  • Cai-Dian Lu
  • Carl Schmidt
  • Christine McLean
  • Christophe Royon
  • Christopher Schwan
  • Ciaran Williams
  • Claire Gwenlan
  • Cristina Mantilla-Suarez
  • Daniel Reichelt
  • Darren Scott
  • Davide Napoletano
  • Deepak Kar
  • Diego Stocco
  • Duff Neill
  • Duong Nguyen
  • Elliot Reynolds
  • Emma Slade
  • Falko Dulat
  • Frederik Ruehr
  • Garvita Agarwal
  • Giuseppe De Laurentis
  • Herschel Chawdhry
  • Holger Schulz
  • Holly Pacey
  • Hsin-Wei Hsia
  • Hugues Lattaud
  • Ia Iashvili
  • Iain Bertram
  • Ian Moult
  • Jannik Geisen
  • Jennifer Kile
  • Jeong Yeon Yook
  • Jesse Thaler
  • Johannes Michel
  • Johnnes Schlenk
  • Joshua Isaacson
  • Juan Cruz-Martinez
  • Juska Pekkanen
  • Kai Schweda
  • Keping XIE
  • Klaus Rabbertz
  • Lauren Hay
  • Lin Dai
  • Liron Barak
  • Lorenzo Tancredi
  • Maddie McKay
  • Marcel Balsiger
  • Marcello Fanti
  • Marek Schoenherr
  • Marian Heil
  • Marius Höfer
  • Markus Diehl
  • Markus Ebert
  • Martin Kwok
  • Massimiliano Grazzini
  • Matthias Neubert
  • Maxim Pieters
  • Maximiliano Sioli
  • Miguel Arratia
  • Nataliia Zakharchuk
  • Paolo Gunnellini
  • Pavel Nadolsky
  • Pavel Starovoitov
  • Pekka Sinervo
  • Riccardo Nagar
  • Robert Vallance
  • Roberto Mondini
  • Roberval Walsh
  • Salvatore Rappoccio
  • Samuel Abreu
  • Sergey Alekhin
  • Simon Badger
  • Simona Gargiulo
  • Simone Marzani
  • Stefan Prestel
  • Stefano Carrazza
  • Stephen Jones
  • Svenja Pflitsch
  • Tao Han
  • Thomas Cridge
  • Timothy Hobbs
  • Tobias Neumann
  • Ulrich Schubert
  • Valentin Hirschi
  • Veronika Magerl
  • Vincent Theeuwes
  • Vladimir Savinov
  • Wolfgang Altmannshofer
  • Xing Wang
  • Youngjin Kim
  • Zahari Kassabov
    • 7:30 AM

      Jacobs Medical School, foyer

    • 8:00 AM
      Breakfast/Coffee 2nd Floor Atrium

      2nd Floor Atrium

      Light Breakfast Options + Coffee/Tea

    • Plenary Session 2220 A - Chair : Sal Rappoccio

      2220 A - Chair : Sal Rappoccio

      • 1
        Welcome 2200 A (Buffalo, NY)

        2200 A

        Buffalo, NY

        Speaker: Ciaran Williams (SUNY Buffalo)
      • 2
        Higher-order calculations and precision phenomenology 2220 A - Chair : Sal Rappoccio

        2220 A - Chair : Sal Rappoccio

        Speaker: Prof. Massimiliano Grazzini (University of Zurich)
      • 3
        Deep Learning (and Deep Thinking) for QCD 2220 A - Chair : Sal Rappoccio

        2220 A - Chair : Sal Rappoccio

        Speaker: Prof. Jesse Thaler (MIT)
    • 10:40 AM
      Coffee Break Atrium (Jacobs Medical School,)


      Jacobs Medical School,

      Morning Coffee break

    • Plenary Session 2220 A - Chair : Jesse Thaler

      2220 A - Chair : Jesse Thaler

      • 4
        Overview of new Higgs results
        Speaker: Liron Barak
      • 5
        Recent developments in PDFs
        Speaker: Dr Zahari Kassabov (University of Cambridge)
    • 12:30 PM
      Lunch (on site) Atrium, Jacobs Medical School

      Atrium, Jacobs Medical School

      Lunch provided

    • Jets/Sub/Res: Jets/Sub/Res Parallel 2213 B Chair : Deepak Kar

      2213 B Chair : Deepak Kar

      • 6
        Measurement of jet substructure observables using the ATLAS detector
        Theoretical calculations for jet substructure observables with accuracy beyond leading-logarithm have recently become available. Such observables are significant not only for probing a new regime of QCD at a hadron collider, but also for improving the understanding of jet substructure properties that are used in many searches for physics beyond the Standard Model. In this talk, we discuss a first measurement of such jet substructure quantities. The soft drop mass is measured in dijet events with the ATLAS detector at √s=13 TeV, unfolded to particle-level and compared to Monte Carlo simulations. We also present a measurement of substructure variables in ttbar and inclusive jet events, using data collected by the ATLAS experiment at √s = 13 TeV. The measurements are performed with large-radius jets. They are corrected for detector effects, represented as particle-level distributions and are compared to the predictions of various Monte Carlo event generators. If available, a measurement of jet substructure observables performed using charged particles, at √s = 13 TeV, is also presented. New event generator configurations for the modelling of jet production, derived using ATLAS data will also be presented.
        Speaker: Prof. Iain Bertram (Lancaster University)
      • 7
        Leading and sub-leading jet functions and applications
        For many high-energy processes at the LHC involving hadronic final states, one often encounters jet functions in the factorisation theorems which can be used to resum various logarithmically enhanced contributons. The resummation of jet radius logarithms has been studied before for inclusive jet production and exclusive jet production. We investigate what happens in the transition between these cases and examine jet functions for leading, and sub-leading jet production. We will also discuss some phenomenological implications in Higgs + 1 jet production as well as other processes.
        Speaker: Darren Scott (University of Amsterdam/Nikhef)
      • 8
        Jet gap jet cross sections at the LHC
        We will present new calculations of the jet gap jet cross sections at the LHC using the BFKL NLL formalism and comparisons between Tevatron D0 and CDF data. Predictions for jet gap jet cross sections at the LHC will also be given. For the first time, predictions will include NLO impact factors, which is absolutely needed in order to compare with data. New numerical methods were used in order to understand the effects of NLO impact factors. Jet gap jet cross section calculations with one intact proton in the final state will also be presented.
        Speaker: Christophe Royon
      • 9
        $N$-subjettiness for boosted jets
        In this talk I will show how the resummation for the jet mass, in the presence of a cut on some jet-shape, can be extended to the region where this cut takes some finite value, which often represents a more realistic situation. In particular, and to highlight the main points, I will focus on $N$-Subjettinss with $\beta=2$, although the method is, in principle, completely general.
        Speaker: Davide Napoletano (IPht, CEA Saclay)
      • 10
        Fitting the strong coupling constant for soft-drop thrust
        Over the years many different types of fits for the strong coupling constant have been performed. However one type of high precision result that currently significantly differs from the world average are results from event shapes at electron positron colliders. One possible source for the difference in these results could be the degeneracy between the fit of the strong coupling constant and non-perturbative parameters. In this talk I will explore the application of modern jet substructure techniques, specifically soft drop, in order to break the impact of the non-perturbative corrections on the fit of the strong coupling constant.
        Speaker: Vincent Theeuwes (University of Goettingen)
    • PDFs/Soft/Alpha_S I 2220 A Chair : Stefano Carrazza

      2220 A Chair : Stefano Carrazza

      • 11
        A new generation of parton distribution functions with deep learning models
        We show recent developments on new methodologies for the determination of Parton Distribution Functions in the context of the NNPDF collaboration. We study different models and architectures in a systematic way which allows as to assess the quality of the fit: overtraining, model complexity, hyperparameter setup, optimization algorithm... We show a fully automatized pipeline to achieve a best model setup finding good improvements in both the quality and efficiency of the fits.
        Speaker: Mr Juan Cruz-Martinez (University of Milano)
      • 12
        CTEQ-TEA parton distributions with the LHC data
        I summarize results of a new global QCD analysis CT18 that includes a large number of new LHC experiments.
        Speaker: Pavel Nadolsky (SMU)
      • 13
        Updates on PDFs in the MMHT framework
        We discuss updates to the MMHT2014 and 2016 PDFs ahead of a new release of PDF sets. These updates include the addition of further data, largely from the LHC, as well as a consequent extension of our PDF parametrisation. We also summarise the results of our inclusion of QED effects in parton distributions.
        Speaker: Dr Thomas Cridge (Univeristy College London)
      • 14
        NNLO QCD fits to extract PDFs from HERA inclusive and jet data
        NNLO predictions for jet production in Deep Inelastic Scattering have recently become available. These are used to extend the QCD HERAPDF2.0Jets fits, that were made to extract PDFs from inclusive HERA data and HERA jet data, from NLO to NNLO.  In addition new jet data sets have become available since the publication of HERAPDF2.0 and these are also considered.
        Speaker: Claire Gwenlan (Oxford)
      • 15
        Measurements of single diffraction using forward proton tagging at ATLAS
        Inclusive single diffractive dissociation (pp->pX) is studied using data collected by the ATLAS experiment at the LHC. The intact proton is reconstructed and measured in the ALFA forward spectrometer, while charged particles from the dissociative system (X) are reconstructed and measured using the ATLAS inner tracking detector and calorimeters. Differential cross sections are presented as a function of the proton fractional momentum loss, the four-momentum transfer squared, and the size of a rapidity gap measured from the edge of the ATLAS calorimeters. The results are interpreted in the framework of Regge phenomenology.
        Speaker: Dr Antonio Sbrizzi (INFN Bologna)
    • pQCD/MC: pQCD/MC Parallel 2213 A Chair : Marek Schoenherr

      2213 A Chair : Marek Schoenherr

      • 16
        Modeling of top quark and vector boson production as backgrounds to Higgs boson decays to b-quarks
        The modeling of top quark production (ttbar and single-top) and vector boson production (W/Z) in association with heavy flavor jets constitutes one of the largest uncertainties in the extraction of a Higgs to b-quarks signal at the LHC, and is thus a crucial aspect to address on the way from the observation of this decay to precise differential measurements. This talk will give an overview of how these backgrounds are currently dealt with in the VH, Higgs to bb analysis, the impact of their modeling uncertainties on the most recent inclusive and differential results, and provide an outlook about where improved predictions are needed to overcome the current limitations.
        Speaker: Mrs Simona Gargiulo (Albert-Ludwigs-Universität Freiburg)
      • 17
        High Energy resummation for Higgs plus dijets
        Higgs boson production in association with two jets is an interesting process to measure the Higgs to weak-boson coupling (WBF). However at the LHC the inclusive production of Hjj is dominated by the gluon fusion component, where the Higgs boson couples to the gluon via a top loop. The gluon fusion component is typically reduced by cuts requiring a large invariant dijet mass. Such mass cuts force the phase space in a region of large rapidity separations between the jets, where a logarithm $\ln(s/t)$ becomes relevant. I will present the latest efforts of resumming even Next-to-Leading logarithmic contributions, as implemented in the generator High Energy Jets (HEJ). Since the limit of large top-mass and the high energy limit commute, the full top mass dependence can be retained in the predictions. The effect of the finite top mass is a further 10% reduction of the cross section, on top of the ~40% reduction within the WBF cuts of the results obtained with the HEJ resummation compared to the results at NLO.
        Speaker: Mr Marian Heil (IPPP Durham)
      • 18
        NNLO precision phenomenology with MCFM
        We present newest advancements in MCFM 9.0 for per-mille level precision physics at NNLO. A focus of this update is determining precise predictions of PDF uncertainties at NNLO and differences between PDF sets at NNLO accuracy. We also present performance improvements for all NNLO processes through the inclusion of power corrections and an improved integration that enable such studies.
        Speaker: Tobias Neumann
      • 19
        Robust uncertainty estimation in MC tuning
        We propose a robust way of estimating and propagating uncertainties in the "tuning" of Monte Carlo event generator simulations to describe experimental data. This approach enhances the established eigentunes method by using a statistically sound coverage measure rather than an ad hoc tolerance scale to determine the size of parameter variations allowed by the data. The efficacy of the new scheme, and wider reflections on the nature of tuning and MC uncertainties, will be illustrated by application of the Professor tool to toy and real tuning problems.
        Speaker: Dr Andy Buckley (University of Glasgow)
      • 20
        Vector boson pair production at the LHC: NLO QCD corrections to the loop-induced gluon fusion channel
        We consider the QCD cross section for vector boson pair production at the LHC, including off-shell effects, interferences and leptonic decays. The loop-induced gluon fusion production is quantitatively relevant in this process despite the fact that it enters at the second order in the QCD coupling. We present new results for the NLO corrections to the gluon fusion contribution for ZZ and WW production, including, for the first time, the qg partonic channel. Together with the NNLO corrections to quark-antiquark annihilation, we obtain an approximate N3LO prediction for these processes. The computation is carried out within the MATRIX framework.
        Speaker: Ms Jeong Yeon Yook (University of Zurich)
    • 4:10 PM
      Afternoon Coffee Break
    • Higgs/EW/BSM 2213 B Chair : Falko Dulat

      2213 B Chair : Falko Dulat

      • 21
        QCD Issues in Searches for Supersymmetry with the ATLAS Detector
        Despite the absence of experimental evidence, weak-scale supersymmetry remains one of the best motivated and studied Standard Model extensions. Searches for weak-scale supersymmetry interact with QCD in many ways: QCD scaling rules are used in background estimation techniques; jet sub-structure is exploited for separating signal and background; signal cross sections rely on higher-order calculations and resummation. Additional complex QCD issues arise in searches for R-hadrons, hadrons that include long-lived SUSY particles. This talk summarizes recent ATLAS results on supersymmetry searches, focusing on those aspects that most strongly interact with QCD.
        Speaker: Ms Veronika Magerl (University of Freiburg)
      • 22
        A Monte Carlo analysis of the SMEFT in the top quark sector
        We present a novel framework to carry out global analyses of the Standard Model Effective Field Theory (SMEFT) at dimension-six: SMEFiT. The SMEFiT approach is based on the Monte Carlo replica method to derive a faithful estimate of the experimental and theoretical uncertainties and enables one to construct the probability distribution in the space of the SMEFT degrees of freedom. As a proof of concept of the SMEFiT methodology, we present an extensive study of the constraints on the SMEFT provided by top quark production measurements from the LHC. Our analysis includes more than 30 independent measurements from 10 different processes at $\sqrt{s}=8$ and 13 TeV, including inclusive $t\bar{t}$ and single-top production and the associated production of top quarks with vector bosons and the Higgs boson. State-of-the-art theoretical calculations are adopted both for the SM and the SMEFT contributions, where in the latter case NLO QCD corrections are included for the majority of processes. We derive bounds for the 34 degrees of freedom relevant for the interpretation of top quark data and compare these bounds with previously reported constraints. Our study illustrates the significant potential of LHC precision measurements to constrain physics beyond the Standard Model in a model-independent way, and pave the way towards a global analysis of the SMEFT.
        Speaker: Ms Emma Slade (University of Oxford)
      • 23
        New tools to look for multi-jet resonances
        Abstract:Finding multi-jets resonances at LHC is almost impossible, due to the huge QCD multi-jet backgrounds. We have created new techniques for these searches that suppress QCD backgrounds. Our tools make use of the rich information from the internal kinematics of multi-jet decays to form Dalitz variables. These variables can be used to identify inherent differences in multi-jet topologies from QCD and signal. We implement these techniques in a dataset taken using the CMS detector with low thresholds (Data Scouting) and were sensitive to BSM signatures at 200 GeV. We are extending these Dalitz techniques to identify the jet substructure in boosted signal decays. This would enable us to search for even lower mass resonances.
        Speaker: Abhijith Gandrakota
      • 24
        Localized 4𝜎 and 5𝜎 Dijet Mass Excesses in ALEPH LEP2 Four-Jet Events
        We investigate an excess observed in hadronic events in the archived LEP2 ALEPH data. The events are clustered into four jets and paired such that the mass difference between the two dijet systems is minimized. The excess occurs in the region M1+M2∼110 GeV; about half of the excess is concentrated in the region M1∼80 GeV, M2∼25 GeV, with a local significance between 4.7σ and 5.5σ, depending on assumptions about hadronization uncertainties. The other half of the events are in a broad excess near M1∼M2∼55 GeV; these display a local significance of 4.1−4.5σ. We investigate the effects of changing the SM QCD Monte Carlo sample, the jet-clustering algorithm, and the jet rescaling method, finding that the excess is remarkably robust under these changes, and we find no source of systematic uncertainty that can explain the excess. No analogue of the excess is seen at LEP1. We conclude that this excess should be investigated by the other LEP experiments and that QCD experts should study whether or not this effect can be reproduced by QCD Monte Carlo generators.
        Speaker: Dr Jennifer Kile (none)
    • PDFs/Soft/Alpha_S I 2220 A Chair : Paolo Gunnellini

      2220 A Chair : Paolo Gunnellini

      • 25
        PDF-independent Electroweak and Photon-induced Theoretical Predictions
        Storing theoretical predictions for collider observables independent from PDFs is a worthwhile goal from at least two different perspectives: As a theorist producing the theoretical predictions this enables one to quickly change the PDF set and thereby to assess possible differences of the PDF sets. From the perspective of someone fitting a new PDF set, the PDF-independent theoretical predictions are one neccessary ingredient of the fitting procedure. The problem described above is well-known and solved for QCD in the public frameworks APPLgrid and fastNLO. Two points which are so far unaddressed, however, are the treatment of electroweak corrections and the inclusion of photon-induced contributions. They will become important because the next generation of PDFs are about reach a level of precision where the inclusion of next-to-leading order electroweak effects becomes important. In this talk I am going to describe the problem in more detail and the status of our effort addressing it.
        Speaker: Mr Christopher Schwan (Universita degli Studi di Milano)
      • 26
        Interpolation and evolution of parton distribution functions with ChiliPDF
        We present an efficient implementation of the solution of the DGLAP equations for single and double parton distributions (PDFs and DPDs). The implemented algorithm is based on the Chebyshev interpolation of these functions. For PDF evolution, our method allows for a higher numerical accuracy using a considerably smaller amount of grid points compared to existing methods. As a consequence of the high interpolation accuracy, operations on PDFs such as differentiation and Mellin convolution can be done in a fast way and with a high level of precision. Furthermore, the DPD evolution is realized to a satisfactory degree of accuracy using an affordable number of points, and allows for two independent renormalization scales for the two partons. For both PDFs and DPDs, DGLAP evolution and flavor matching are implemented up to NNLO.
        Speaker: Riccardo Nagar (DESY)
      • 27
        Application of the APPLfast grid interface to NNLOJET and determination of alpha_s(M_Z) at NNLO from DIS jet cross sections
        The technique of interpolation grids as implemented in the APPLgrid or fastNLO packages provides a fast and flexible way to reproduce the results of perturbative QCD cross section calculations with any input PDF, choice of scales, or strong coupling constant. Recent developments in the APPLfast interface between the NNLOJET QCD calculation with both packages are reported. As an example results using precision interpolation grids for a number of jet production processes at HERA are presented and the strong coupling constant, alphas(MZ), is determined at next-to-next-to-leading order QCD from inclusive jet cross section data in electron-proton collisions. The required NNLO interpolation grids shall be made publically available via the ploughshare utility that is discussed as a standard source for the distribution of such grids. Development versions of grids for QCD cross sections at the LHC including jet production and Z production at high pT are available as well.
        Speaker: Klaus Rabbertz (ETP, KIT, Karlsruhe, Germany)
      • 28
        Experimental constraints on collinear PDFs at 7, 8, 13 TeV (W, Z, jet production) by CMS
        Experimental constraints on collinear PDFs at 7, 8, 13 TeV (W, Z, jet production) by CMS are presented.
        Speaker: Svenja Pflitsch (Deutsches Elektronen Synchrotron (DESY))
      • 29
        Determination of proton parton distribution functions and extraction of alpha_S using ATLAS data
        We present fits to determine parton distribution functions (PDFs) using top-antitop, inclusive W/Z-boson, as well as W+ and W− boson production measurements in association with jets from ATLAS, in combination with deep-inelastic scattering data from HERA. The ATLAS W and Z boson data exhibit sensitivity to the valence quark distributions and the light quark sea composition, whereas the top-quark pair production data have sensitivity to the gluon distribution. The impact of the top-antitop production data is increased by fitting several distributions simultaneously, with the full information on the systematic and statistical correlations between data points. The parton distribution functions extracted using W+jets data show an improved determination of the high-x sea-quark densities, while confirming the unsuppressed strange-quark density at lower x<0.02 found by previous ATLAS analyses. We also present a measurement of the rapidity and transverse momentum dependence of dijet azimuthal decorrelations, using the quantity RΔϕ. This quantity specifies the fraction of the inclusive dijet events in which the azimuthal opening angle of the two jets with the highest transverse momenta is less than a given value of the parameter Δϕmax. RΔϕ is measured in proton-proton collisions at √s=8 TeV as a function of the dijet rapidity interval, the event total scalar transverse momentum, and Δϕmax. The data are used to determine the strong coupling αS and to study its running for momentum transfers from 260 GeV to above 1.6 Te
        Speaker: Claire Gwenlan (Oxford)
    • pQCD/MC: pQCD/MC Parallel 2213 A Chair : Andy Buckley

      2213 A Chair : Andy Buckley

      • 30
        Isolated photon and photon+jet production at NNLO QCD accuracy
        Based on 1904.01044, I present recent results of a Next-to-Next-to-leading order (NNLO) calculation of inclusive isolated photon and photon-plus-jet production using the Monte-Carlo event generator NNLOJET. In order to mimic experimental photon isolation criteria we apply a staged isolation procedure. A smooth-cone isolation with small cone size is used to ensure numerical stability, followed by a hard-cone isolation with larger cone size, tailored to the actual experimental setup. We compare the results to recent 13TeV data by ATLAS (1701.06882, 1801.00112, 1901.10075) and CMS (1807.00782). We observe substantial corrections in certain kinematical regions, leading to a significant improvement of theory uncertainty and description of the data.
        Speaker: Mr Marius Höfer (Universität Zürich)
      • 31
        Power corrections for qT and TauN subtractions from photon isolation
        Photon isolation cuts are crucial for measuring direct photon production to reduce background from hadron fragmentation. The isolation is commonly implemented by vetoing hadronic radiation around the photons. We discuss how this affects the $q_T$ and ${\cal T}_N$ subtraction methods for fixed-order calculations, which are based on analytically integrating over soft and collinear radiation. In particular, we show that the isolution can induce much larger power corrections than naively expected, and discuss how these corrections depend on the chosen isolation parameters.
        Speaker: Markus Ebert (MIT)
      • 32
        Measurement of photon production at ATLAS
        The production of prompt isolated photons at hadron colliders provides stringent tests of perturbative QCD and can be used to evaluate probability density functions of partons in the proton. In this talk, we present the measurements of the isolated-photon plus two jets and the inclusive isolated-photons cross sections, both measured using proton-proton collision data collected by the ATLAS experiment at √s=13 TeV. A ratio of photon cross sections at √s=8 and √s=13 TeV will also be presented. The results are compared with state-of-the-art theory predictions, indicating several interesting discrepancies.
        Speaker: Prof. Marcello Fanti (Universita` degli Studi di Milano)
      • 33
        Isolated photons and jets measurements with the ALICE detector in the LHC
        I will present the results of the production of isolated photons and jets measured with the ALICE detector in proton-proton and proton-lead collisions at the LHC. These serve as reference points for perturbative QCD calculations, and for extracting nuclear modifications of fragmentation functions and PDFs. The ALICE detector complements other experiments at the LHC by covering a kinematic domain of lower transverse momentum, and therefore lower Q2, which is the region where larger nuclear effects are expected.
        Speaker: Miguel Arratia (UC Berkeley)
      • 34
        Studying minijets and multiple parton interactions with rapidity correlations
        A short review of phenomenological models of Multiple Parton Interactions (MPI) implemented in the three main Monte Carlo generators: Herwig, Pythia, and Sherpa will be given. New observables which are sensitive to different mechanisms of mini-jet production and MPI physics will be introduced. The observables measure how the transverse momenta of hadrons produced in association with various trigger objects are balanced against it as a function of rapidity. It will be demonstrated that the Monte Carlo generators show significantly different predictions for the proposed observables. Finally, a measurement of the proposed rapidity correlations performed by the CMS Collaboration will be discussed
        Speaker: Andrzej Siodmok (IFJ PAN)
    • 8:00 AM
      Breakfast + Coffee 2nd Floor Atrium

      2nd Floor Atrium

    • Plenary Session: Plenary Session I 2220 A Chair : Massimiliano Grazzini

      2220 A Chair : Massimiliano Grazzini

      • 35
        Jet and photon+jet physics
        Speaker: Mr Hugues Lattaud (Université Claude Bernard Lyon 1)
      • 36
        IR singularities of scattering amplitudes at 3 and 4-loop order
        Speaker: Matthias Neubert (Johannes Gutenberg University Mainz)
      • 37
        Constraints on PDFs from LHC measurements
        Speaker: Svenja Pflitsch (Deutsches Elektronen Synchrotron (DESY))
    • 10:45 AM
    • Plenary Session: Plenary Session II 2220 A Chair : Matthias Neubert

      2220 A Chair : Matthias Neubert

      • 38
        Computing for the LHC
        Speaker: Holger Schulz
      • 39
        Review of Resummation
        Speaker: Ian Moult (Lawrence Berkeley Laboratory)
    • 12:30 PM
    • Heavy Quarks/Top 2213 B Chair : Wolfgang Altmannshofer

      2213 B Chair : Wolfgang Altmannshofer

      • 40
        Associated production of a top quark pair with a heavy boson at NLO+NNLL accuracy
        The production processes of top quark pair in association to a heavy boson are important studies at the LHC. These types of processes are important in order to directly study the interaction between the top quark and the massive boson. Therefore increased theoretical accuracy is of vital importance. In this talk recent precision theoretical predictions at NLO+NNLL accuracy for these processes are presented.
        Speaker: Vincent Theeuwes (University of Goettingen)
      • 41
        QCD Calculation for hadronic B decays
        All B decays are electroweak decays, but their QCD calculations are very complicated, due to large non-perturbative effects. Since the b quark mass is heavy, we can use a perturbative expansion of 1/m_b to prove factorization. After many years development, theory of hadronic B decays has been developed well using factorization. I will summarize the current situation and recent progress including the QCD factorization, perturbative QCD factorization and factorization assisted topological diagram approach for the hadronic B decays.
        Speaker: Prof. Cai-Dian Lu (IHEP, Beijing)
      • 42
        Highlights of top-quark production measurements at ATLAS
        Measurements of inclusive and differential cross-sections of top-quark production in proton-proton collisions at centre-of-mass energy of 13 TeV with the ATLAS detector at the Large Hadron Collider are presented. Single top-quark and top-quark pair final states as well as top-quark production in association with heavy flavor jets, vector bosons and a photon are discussed.The measurements reach high precision and are compared to the most precise available theoretical calculations.
        Speaker: Prof. Pekka Sinervo (University of Toronto)
      • 43
        Highlights of top-quark properties measurements at ATLAS
        The top quark is the heaviest known fundamental particle. As it is the only quark that decays before it hadronizes, this gives the unique opportunity to probe the properties of bare quarks. This talk will focus on a few recent precision measurements of top quark properties in top-quark pair and single top-quark events by the ATLAS Collaboration. Among these is the measurement of spin correlations in ttbar pair production. Measurements of the top quark mass and searches for rare top-quark interactions are also presented.
        Speaker: Mr Robert Vallance (University of Birmingham)
      • 44
        Heavy-flavor production at hadron colliders
        We develop Simplified-ACOT scheme with Massive Phase Space (SACOT-MPS), which is a general-mass variable flavor number scheme (GM-VFNS), to deal with heavy-flavor production at hadron colliders. By following the idea of Simplified-ACOT-chi scheme in the deep inelastic scattering (DIS), we categorize the open heavy-flavor diagrams into Flavor Excitation (FE) and Flavor Creation (FC). The overlapped diagrams are subtracted by the collinear splitting in order to avoid double-counting. The Flavor Creation terms can be extracted from Fixed Flavor Number Scheme (FFNS), while the Flavor Excitation terms and Subtraction (SB) terms involve the initial heavy-flavor parton scattered by another light parton (light quark or gluon). We introduce the massive phase space for the FE and SB, which accounts for the threshold effect of massive heavy quark. The massive phase space regulates the singular behavior for pT->0, which stabilizes the cancellation between FE and SB in this limit and leads a smooth transition to the FFNS as a result. The numerical results provide a good agreement with the LHCb measurement of B-meson production.
        Speaker: Keping Xie (Southern Methodist University)
    • Higgs/EW/BSM: Higgs 2213 A Chair : Alessandro Vicini

      2213 A Chair : Alessandro Vicini

      • 45
        Precise predictions for Higgs rapidity distribution at N3LO
        I will discuss the computation of the Higgs rapidity distribution at N$^3$LO in the gluon fusion production mode. Our approach relies on the fully analytic computation of six terms in a systematic expansion of the partonic differential cross section around the production threshold of the Higgs boson at next-to-next-to-next-to leading order in QCD perturbation theory. We observe a mild correction compared to previous perturbative order and a significant reduction of the dependence of the cross section on the perturbative scale throughout the entire rapidity range.
        Speaker: Mr Andrea Pelloni (ETHZ)
      • 46
        N3LO predictions for the decay of the Higgs boson to bottom quarks
        We present a fully-differential calculation of the $H \to b\overline{b}$ decay at next-to-next-to-next-to-leading order (N3LO) accuracy. Our calculation considers diagrams in which the Higgs boson couples directly to the bottom quarks. In order to regulate the infrared divergences present at this order we use the Projection-to-Born technique coupled with N-jettiness slicing. After validating our methodology at next-to-next-to-leading order (NNLO) we present exclusive jet rates and differential distributions for jet observables at N3LO accuracy using the Durham jet algorithm in the Higgs rest frame.
        Speaker: Mr Roberto Mondini (University at Buffalo)
      • 47
        Measurement of associated production of a heavy boson (Z/W/Higgs) with two top quarks
        The measurement of the associated production of a heavy boson with two top quarks (ttbar+W/Z/Higgs) allows for stringent tests of perturbative QCD. This talk presents the most recent cross section measurements of tt+W/Z/H production performed by the ATLAS experiment based on the he pp collision dataset collected at 13 TeV, and comparison to the state-of-the-art theory predictions.
        Speaker: Jannik Geisen (II. Physikalisches Institut, Georg-August-Universität Göttingen)
      • 48
        Charm-quark Yukawa Coupling in $h\rightarrow c\bar{c}\gamma$ at LHC
        It is extremely challenging to probe the charm-quark Yukawa coupling at hadron colliders primarily due to the large Standard Model (SM) background (including $h\to b\bar b$) and the lack of an effective trigger for the signal $h\to c\bar c$. We examine the feasibility of probing this coupling at the LHC via a Higgs radiative decay $h\rightarrow c\bar{c}\gamma$. The existence of an additional photon in the final state may help for the signal identification and background suppression. Adopting a refined triggering strategy and utilizing basic machine learning, we find that a coupling limit of about 8 times the SM value may be reached with $2\sigma$ sensitivity after the High Luminosity LHC (HL-LHC). Our result is comparable and complementary to other projections for direct and indirect probes of $h\to c\bar c$ at the HL-LHC. Without a significant change in detector capabilities, there would be no significant improvement for this search from higher energy hadron colliders.
        Speaker: Xing Wang (University of Pittsburgh)
      • 49
        Higgs interference effect at the one-loop level in the 1-Higgs-Singlet extension of the Standard Model
        A detailed study of Higgs interference e?ffects at the one-loop level in the 1-Higgs-Singlet extension of the Standard Model (1HSM) is presented for the WW and t?t decay modes with fully leptonic WW decay. We explore interference effects for benchmark points with a heavy Higgs mass that significantly exceeds 2mt. In the WW channel, the Higgs signal and the interfering continuum background are loop induced. In the t?t channel, which features a tree-level background, we also calculate the interference with the one-loop background, which, due to the appearance of the absorptive part, is found to dominate the normalization and shape of di?fferential Higgs distributions and should therefore be considered in experimental analyses. The commonly used geometric average K-factor approximation is not appropriate. We calculate with massive top and bottom quarks. Our 1HSM and SM implementation in Sherpa+OpenLoops is publicly available and can be used as parton-level integrator or event generator.
        Speaker: Dr WEIMIN SONG (Rutherford Appleton Laboratory)
    • Jets/Sub/Res: Grooming/Substructure 2220 A Chair : Christine MClean

      2220 A Chair : Christine MClean

      • 50
        Jet grooming with reinforcement learning
        We introduce a novel implementation of a reinforcement learning algorithm which is adapted to the problem of jet grooming, a crucial component of jet physics at hadron colliders. We show that the grooming policies trained using a Deep Q-Network model outperform state-of-the-art tools used at the LHC such as Recursive Soft Drop, allowing for improved resolution of the mass of boosted objects. The algorithm learns how to optimally remove soft wide-angle radiation, allowing for a modular jet grooming tool that can be applied in a wide range of contexts.
        Speaker: Dr Stefano Carrazza (University of Milan)
      • 51
        Quarkonium Production in Jets at the LHC
        We study quarkonium production within jets based on the fragmenting jet function (FJF) formalism which describes the distribution of a quarknium in a jet with certain jet shape. FJF incorporates quarkonium fragmentation functions which can be obtained using NRQCD factorization formalism. Thus, the study of quarkonium production in jets also provides a test of NRQCD. In this talk, I will discuss the applications of this formalism to the analysis of recent data from LHC.
        Speaker: Dr Lin Dai (Duke University)
      • 52
        Measurement of jet fragmentation using the ATLAS detector
        Gluon splitting to b-quark pairs is a unique probe of the properties of gluon fragmentation, as the identified b-tagged jets provide a proxy for the quark daughters of the initial gluon. We present a measurement of key differential distributions related to g→b bbar using data collected with the ATLAS detector at √s=13 TeV. Track jets are used to probe angular scales below the standard R=0.4 jet radius. The observables are unfolded to particle level in order to facilitate direct comparison with predictions from simulations and provide an important constraint to hadronization models. A measurement of the properties of jet fragmentation performed with proton-proton collision data collected with the ATLAS detector at √s=13 TeV will also be presented. Charged particle tracks are used to measure charged particle multiplicity, the jet charge, the summed fragmentation function, the momentum transverse to the jet axis, and the radial profile of the jet. Each observable is unfolded to correct for acceptance and detector effects. Exclusive interpretations in terms of quarks and gluons are provided in order to directly compare with state-of-the-art calculations.
        Speaker: Dr Andy Buckley (University of Glasgow)
      • 53
        ResBos2: Status Update
        I will discuss the current status of the ResBos 2 project. The focus will be on accuracy of the resummation calculation, and the comparison to LHC data for $p_T$, $\phi^*_\eta$, and the angular coefficients for Drell-Yan. In addition, details pertaining to the ongoing studies of the detailed theoretical uncertainties that arise from the resummation calculation in the measurement of the $W$ boson mass, along with the ratio of the $Z$ transverse momentum to the $W$ tranvserse momentum will be discussed.
        Speaker: Joshua Isaacson
      • 54
        Measurements of jet mass and substructure at CMS
        Speaker: Ms Ashley Parker (SUNY Buffalo)
    • 4:05 PM
    • Heavy Quarks/Top 2213 B Chair : Pekka Sinervo

      2213 B Chair : Pekka Sinervo

      • 55
        Measurement of the Jet Mass Distribution in Boosted Top Quark Decays in CMS
        Speaker: Mr Paolo Gunnellini (Hamburg University)
      • 56
        On the ambiguities of the BLM/PMC procedure for hadron collider processes
        In perturbative Quantum Chromodynamics calculations, theoretical uncertainties are ascribed to ambiguities over the choice of the renormalisation scale, $\mu_R$. The BLM/PMC scale-setting procedure is one proposed method to remove this ambiguity. In this work, three ambiguities are identified in the BLM/PMC procedure itself and their numerical impact is studied using the example of the inclusive cross-section for $t\bar{t}$ production. One ambiguity is the arbitrary choice of the value of the highest-order PMC scale, $q_4$. The numerical impact of the choice of $q_4$ on the BLM/PMC prediction for the cross-section is found to be comparable to the impact of the choice of $\mu_R$ in the conventional scale-setting approach.
        Speaker: Herschel Chawdhry (University of Cambridge)
      • 57
        ATLAS results on Spectroscopy and Production in Heavy Flavour, including Onia
        The associated production of vector boson with quarkonia is a key observable for understanding the quarkonium production mechanisms, including the separation of single and double parton scattering components. This talk will present the latest measurements from ATLAS on quarkonium production, including associated production. In addition, searches for, and measurements of exotic states are studied, and recent results from heavy flavour spectroscopy are reported.
        Speaker: Dr WEIMIN SONG (Rutherford Appleton Laboratory)
    • PDFs/Soft/Alpha_S I 2220 A Chair : Pavel Nadolsky

      2220 A Chair : Pavel Nadolsky

      • 58
        Measurement of the QCD coupling constant by CMS
        The measurement of the QCD coupling constant by CMS is presented.
        Speaker: Dr Juska Pekkanen (SUNY Buffalo)
      • 59
        Probing parton distribution functions at future colliders
        The Large Hadron-electron Collider (LHeC) is a proposed upgrade of the LHC at CERN. An ERL will provide electrons to collide with the HL-LHC, HE-LHC and the FCC-hh proton beams to achieve centre-of-mass energies 1.3-3.5 TeV and luminosities ~10^34 cm-2s-1. These three configurations will extend the kinematic plane by more than one order of magnitude towards smaller x and larger Q2 than HERA. DIS measurements in such machines offer unprecedented possibilities to enlarge our knowledge on parton densities through a complete unfolding of all flavours in a single experimental setup to be compared with data from hadron colliders as an independent input and as a test of factorisation, and to determine alpha_s. In this talk we review the most recent developments on these subjects.
        Speaker: Claire Gwenlan (Oxford)
      • 60
        Updating and Optimizing Error PDFs with ePump
        We present a a software package, ePump (error PDF Updating Method Package), that can be used to update or optimize a set of PDFs, including the best-fit and Hessian eigenvector pairs of PDF sets, and also to update any other set of observables, in the Hessian approach. After validating the program with a comparison against a full global analysis, we use ePump to estimate the impact of several recent LHC data, including measurements of W and Z boson and top quark pair differential distributions, on the CT14HERA2 PDFs.
        Speaker: Carl Schmidt (Michigan State University)
      • 61
        PDF constraints from heavy-flavor production by CMS
        PDF constraints from heavy-flavor production by CMS are presented
        Speaker: Duong Nguyen
      • 62
        Exploring experimental constraints on PDFs with PDFSense
        With the conclusion of Run 2 in 2018, the LHC has now recorded a wealth of data well exceeding 100 fb$^{-1}$. In conjunction with the substantial output from other recent experiments at facilities like HERA and FNAL, these LHC data are an opportunity, as well as a challenge, for particle phenomenology. Incorporating new measurements into QCD global analyses of nucleon PDFs is difficult due to the significant computational cost of fitting, the problem of identifying the highest-impact data upon which to concentrate efforts, and the theory requirements to suitably describe the data. While a number of numerical approaches like Bayesian reweighting exist to ameliorate these issues, we have recently developed a novel, complementary analysis framework, $\tt{PDFSense}$, to rapidly assess the potential constraining power of candidate data sets being considered for inclusion in PDF fits. The advantage of this method is its ability to make common-basis comparisons of many measurements simultaneously, using published error PDFs, and allowing a quantitative visualization of the origin and interplay of the pulls from various empirical data with low computational cost. In this capacity, $\tt{PDFSense}$ played an important role in identifying the highest-impact data from LHC Run I, and helped guide their implementation in the upcoming CT18 global analysis. In this talk, we use the $\tt{PDFSense}$ framework to provide an overview of the phenomenology and pulls of the LHC data, and examine the PDF constraints expected from the future HL-LHC, LHeC, and EIC programs.
        Speaker: Dr Timothy Hobbs (CTEQ at SMU)
    • pQCD/MC: pQCD/MC Parallel 2213 A Chair : Alex Huss

      2213 A Chair : Alex Huss

      • 63
        Higgs Pair Production at High-Energy
        Currently, predictions for Higgs pair production at NLO in QCD including the exact top-quark mass dependence are known only numerically. The numerical calculations have proven to be adequate for making predictions up to moderate values of the Higgs pair invariant mass and Higgs boson transverse momentum. Unfortunately, the numerical calculations can be very compute-intensive to run and can also become increasingly challenging at large invariant mass or transverse momentum. More recently, analytic results valid in the high-energy limit have been computed which can provide important complementary information to the numerical calculations. In this work, after applying a naive Padé approximation which extends the range of validity of the high-energy expansion, we combine the exact numerical results with the expanded results in order to produce a stable prediction valid in the low, medium and high-energy regimes. Improved predictions for hadron colliders with centre-of-mass energies of 14 TeV and 100 TeV are presented.
        Speaker: Dr Stephen Jones (CERN)
      • 64
        Measurement of differential cross sections in Higgs boson decays to bosons using the ATLAS detecto
        With the large pp collision dataset collected at 13 TeV, detailed measurements of Higgs boson production can be performed in decays to bosons. This talk presents measurements of differential cross sections in Higgs boson decays to two photons or to four leptons, and a comparison to state-of-the-art theory predictions.
        Speaker: Maddie McKay (Southern Methodist University)
      • 65
        NLO EW/QCD corrections for WZ scattering at the LHC
        Vector-boson scattering (VBS) denotes an interesting class of processes with small cross sections which recently have been measured or are about to be measured due to the increasing integrated luminosity at the LHC. They allow us to probe the electroweak symmetry breaking, in particular, the interplay between quartic-, triple-, and vector-vector-Higgs couplings. In this talk I will briefly summarise the physics opportunities of VBS and then present the first computation of the NLO EW/QCD corrections to the full off-shell scattering of W and Z, at the LHC contained in the process $\mathrm{p} \mathrm{p} \to \mathrm{e}^+ \nu_\mathrm{e} \mu^+ \mu^- \, \mathrm{j} \mathrm{j} + X$. See also [arXiv:1904.00882][1]. [1]: https://arxiv.org/abs/1904.00882
        Speaker: Mr Christopher Schwan (Universita degli Studi di Milano)
      • 66
        Generalized Threshold Factorization with Full Collinear Dynamics
        In this talk I present a new endpoint factorization theorem that generalizes the classic soft threshold factorization for Drell-Yan-like processes. It fully captures both soft and collinear dynamics, including nondiagonal partonic channels that are neglected in the standard soft limit. This allows us to construct a fixed-order approximant for the cross section that covers all singular limits in the partonic momentum fractions. Our factorization also enables the resummation of all large-$x$ logarithms appearing in the Drell-Yan rapidity spectrum toward large rapidities.
        Speaker: Johannes Michel (DESY Hamburg)
      • 67
        Inclusive jet cross section ratio with respect to jet radius in CMS
        Speaker: Mr Paolo Gunnellini (Hamburg University)
    • 8:00 AM
    • Plenary Session 2220 A Chair : Ciaran Williams

      2220 A Chair : Ciaran Williams

      • 68
        Implications of the Flavor Anomalies
        Speaker: Wolfgang Altmannshofer (UC Santa Cruz)
      • 69
        QCD and BSM in Exotica, Beyond 2 Generations, and SUSY searches in CMS
        This talk will cover an overview of BSM models from the EXO, B2G, and SUS groups at CMS.
        Speaker: Cristina Ana Mantilla Suarez (Johns Hopkins University)
      • 70
        QCD and Searches for Exotic Physics
        Signature-based searches for new physics probe the full range of the collision energy spectrum probed by the Large Hadron Collider. Often the most numerous decays, and thus those with the highest reach in new particle mass, occur in channels with at least one hadronic object and therefore requires control and understanding of the corresponding QCD background. This talk will cover recent search results by the ATLAS experiment highlighting the various techniques used to suppress and understand QCD.
        Speaker: Ms Holly Pacey (University of Cambridge)
    • 10:45 AM
      Coffee Break
    • Plenary Session 2220 A : Chair Claire Gwenlan

      2220 A : Chair Claire Gwenlan

      • 71
        Progress in multi-loop calculations
        Speaker: Dr Lorenzo Tancredi (CERN TH)
      • 72
        Impact of QCD and PDF uncertainties on Standard Model measurements.
        Speakers: Dr Alessandro Tricoli (BNL), Dr Timothy Hobbs (CTEQ at SMU)
    • 1:00 PM
      Lunch (on your own)
    • 2:30 PM
      Bus to Niagara Falls
    • 3:00 PM
      Niagara Falls Visit
    • 5:30 PM
      Bus to Dinner
    • 6:00 PM
      Conference Dinner
    • 8:00 AM
    • Plenary Session 2220 A Chair : Simon Badger

      2220 A Chair : Simon Badger

      • 73
        Experimental measurements of strong coupling at the LHC
        Speaker: Pavel Starovoitov (Kirchhoff Institute for Physics)
      • 74
        Searches for BSM Higgs bosons at the LHC
        Speaker: Roberval Walsh (DESY)
      • 75
        Recent results from ALICE
        Speaker: Dr Kai Schweda (GSI Darmstadt, Germany)
    • 10:45 AM
    • Plenary Session 2220 A Chair : Simone Marzani

      2220 A Chair : Simone Marzani

      • 76
        QCD in W/Z boson + jets events
        Speaker: Nataliia Zakharchuk (Carleton University (CA))
      • 77
        Searches using substructure in LHC
        Speaker: Mr Frederik Ruehr (University of Freiburg)
    • 12:30 PM
    • Jets/Sub/Res: Jets/Sub/Res Parallel 2213 A Chair : Vincent Theeuwes

      2213 A Chair : Vincent Theeuwes

      • 78
        Theory predictions for jet pull
        We discuss the jet shape variable pull and in particular, we present a first-principle prediction for the pull angle, which can help to probe the colour flow between jets. While the pull angle is not infra-red and collinear safe, it is Sudakov safe and therefore it can be calculated using all-order techniques, which share similarities to standard transverse-momentum resummation. We compare our results with Monte Carlo simulations and with the data collected by the ATLAS experiment.
        Speaker: Dr Simone Marzani (Università di Genova & INFN Genova)
      • 79
        Resummation of Jet-Splitting Scales in Multijet Production
        We present predictions for Durham jet resolution scales $y_n$ in multijet production in $e^+e^−$ collisions at NLL accuracy matched to LO. We use the well known CAESAR formalism as a basis and extract the required color information for matrix elements with a large number of jets using tools from the matrix element generator Comix within the Sherpa framework. We discuss the effect of subleading color contributions.
        Speaker: Daniel Reichelt (Göttingen University)
      • 80
        NLL' Resummation of Jet Mass
        Over the last few years, there has been a lot of progress concerning non-global jet observables. Recently, we managed to resum the interjet energy flow and the jet mass at the NLL'-level, meaning that our results include the full next-to-leading-order corrections to the hard, jet and soft functions which are implemented in a parton-shower framework that generates the renormalization-group running in the effective theory. I will explain the implementation of the corrections and present numerical results.
        Speaker: Mr Marcel Balsiger (Institute for Theoretical Physics, University of Bern, Switzerland)
      • 81
        Entropy of Jets
        Scattering processes often inevitably include the production of infra-red states, which are highly correlated with the hard scattering event, and decohere the hard states. The hard reduced density matrix (tracing out infra-red states) has a non-zero entropy. We describe this entropy for an asymptotically-free gauge theory by separating the Hilbert space into hard and infra-red states, and calculate it in a leading-logarithmic approximation for jets. We find that the entropy increases when the resolution scales defining the hard radiation are lowered, that this entropy is related to the subjet multiplicity, and explore connections to using jet images for machine learning, and the forward-scattering density matrix of partons in a nucleon probed in deep-inelastic scattering.
        Speaker: Duff Neill (LANL)
    • pQCD/MC 2220 A Chair : Stefan Prestel

      2220 A Chair : Stefan Prestel

      • 82
        Five particle scattering at two loops in QCD
        I will describe some recent results for two-loop amplitudes with five external legs reconstructed using numerical evaluations over finite fields. This technique avoid many of the bottlenecks of traditional methods and is well suited to amplitudes with many kinematic scales.
        Speaker: Simon Badger (IPPP Durham)
      • 83
        Numerical multi-loop calculations with pySecDec
        PySecDec is a program for the numerical calculation of dimensionally regulated parameter integrals, in particular multi-loop integrals. In this talk new developments in the program such as Quasi-Monte Carlo methods and GPU support will be presented. Applications to multi-loop amplitude calculations will be discussed.
        Speaker: Mr Johannes Schlenk (IPPP)
      • 84
        Master Integrals for $q\bar{q} \rightarrow t\bar{t}$ scattering at NNLO
        The large production rate of top quarks at LHC enables precision studies of top quark observables, which potentially could uncover evidence for new physics. In order to achieve this the precision studies have to be met with equally precise theory predictions. One of the key processes is top quark pair production through the annihilation of a quark pair. While numerical representations already exist at the two-loop level, analytic results remain desirable. In this talk I will report on the analytic calculation of the remaining master integrals needed for this process. In particular I will show how the method of differential equations was employed to calculate the integrals and how the latter can be analytically continued into the top quark production region. The presented calculation completes all ingredients necessary for the two-loop amplitude computation, hence proving that its analytic evaluation is feasible.
        Speaker: Mr Ulrich Schubert (Universtiy at Buffalo)
      • 85
        Extracting analytical amplitudes from numerical evaluations
        I will present a new method (arXiv:1904.04067) to generate analytic expressions for the integral coefficients of loop amplitudes using numerical evaluations only. We use high precision arithmetic to explore the singularity structure of the coefficients and decompose them into parts of manageable complexity. Each part is isolated by choosing an appropriate region of phase space, and reconstructed by solving a system of linear equations for the coefficients of a generic ansatz. To illustrate the usability of our method I will present sample computations for six-gluon one-loop integral coefficients and rational parts.
        Speaker: Mr Giuseppe De Laurentis (IPPP, Durham University)
      • 86
        Colour Reconnection from Soft Gluon Evolution
        We consider soft gluon evolution at the amplitude level to expose the structure of colour reconnection from a perturbative point of view. Considering the cluster hadronization model and an universal Ansatz for the soft anomalous dimension we find strong support for geometric models considered earlier. We also show how reconnection into baryonic systems arises, and how larger cluster systems evolve. Our results provide the dynamic basis for a new class of colour reconnection models for cluster hadronization.
        Speaker: Andrzej Siodmok (IFJ PAN)
    • 4:05 PM
    • Higgs/EW/BSM 2200 A Chair : Ulrich Schubert

      2200 A Chair : Ulrich Schubert

      • 87
        PPS results and prospects from CMS/TOTEM
        We will present the first results and the physics prospects from the CMS Precision Proton Spectrometers namely the observation of exclusive dileptons at high mass, and the search for high mass exclusive diphoton production, as a signal for quartic anomalous couplings and axion like particles at the LHC in the CMS collaboration
        Speakers: Dr Christophe Royon (CEA Saclay), Christophe Royon, Dr Christophe Royon (IRFU-SPP, CEA Saclay)
      • 88
        HL-LHC physics with ATLAS detector
        The Large Hadron Collider (LHC) has been successfully delivering proton-proton collision data at the unprecedented center of mass energy of 13 TeV. An upgrade is planned to increase the instantaneous luminosity delivered by LHC in what is called HL-LHC, aiming to deliver a total of about 3000/fb of data to the ATLAS detector at a center of mass energy of 14 TeV. To cope with the expected data-taking conditions ATLAS is planning major upgrades of the detector. In this contribution we present an overview of the physics reach expected for a wide range of measurements and searches at the HL-LHC for the ATLAS experiment, including Higgs coupling, di-Higgs boson production sensitivity, Vector Boson Scattering prospects as well as discovery potential for electroweak SUSY and other exotic benchmark scenarios. Such studies formed the basis of the ATLAS Collaboration input to the recent HL/HE-LHC Yellow-Report. An executive summary of this report was then submitted as input to the European Strategy process.
        Speaker: Mr Elliot Reynolds (University of Birmingham)
      • 89
        VH(bb) and search for boosted ggH->bb in CMS
        Speaker: Ka hei martin Kwok
      • 90
        Loop Tree Duality for multi-loop numerical integration
        Loop Tree Duality (LTD) offers a promising avenue to numerically integrate multi-loop integrals directly in momentum space by relating them to on-shell trees. I will first present our novel formulation of this duality, applicable systematically and for generic multi-loop integrals. I will then showcase our first numerical results for up to four-loop finite scalar topologies, and conclude by discussing our ongoing work regarding applications to physical loop amplitudes that require an adequate contour deformation and local subtraction of its IR divergences
        Speaker: Dr Valentin Hirschi (ETHZ)
      • 91
        Analytic results for two-loop five-parton amplitudes from numerical unitarity.
        I will discuss the recent calculation of the full set of two-loop five-point amplitudes relevant for phenomenological studies at hadron colliders in the framework of two-loop numerical unitarity. Combined with analytic reconstruction techniques, numerical unitarity can be used to efficiently extract analytic expressions for these amplitudes. Physical constraints allow to simplify these expressions and obtain very compact analytic results.
        Speaker: Mr Samuel Abreu (UCLouvain)
    • PDFs/Soft/Alpha_S I 2213 A Chair : Timothy Hobbs

      2213 A Chair : Timothy Hobbs

      • 92
        Electroweak boson measurements with ALICE
        W and Z bosons are created in the hard scattering processes occurring in the initial stage of heavy-ion collisions and they are insensitive to the presence of a strongly-interactive medium. This makes them a clean probe of the initial-state effects of the collision, such as the nuclear modification of the parton distribution functions (PDFs). The measurement of the electroweak boson production in p-Pb and Pb-Pb collisions at the LHC provides constraints on the nPDFs of the (anti-)quarks in a phase-space region that is poorly constrained by previous experiments. ALICE measures the electroweak boson production in the muonic decay channel in p-Pb and Pb-Pb collisions at large rapidities ($2.5 < y_{lab} < 4$ in the laboratory reference frame). These measurements are complementary to those performed by ATLAS and CMS at mid-rapidity. In this talk, we review the measurements in heavy-ion collisions, with a focus on the most recent results. In particular, the rapidity and centrality dependence of the Z-boson production in Pb-Pb collisions at a center of mass energy per nucleon of $\sqrt{s_{\rm NN}} = 5.02$ TeV will be presented and the status of the analysis of the 2018 data sample will be discussed. The new results on Z-boson production in p-Pb collisions at $\sqrt{s_{\rm NN}} = 8.16$ TeV will be discussed as well. The results will be compared to calculations obtained with or without including the nuclear modifications of the PDFs.
        Speaker: Diego Stocco (Subatech)
      • 93
        Double parton scattering measurements by CMS
        Double parton scattering measurements by CMS are presented.
        Speaker: Mr Maxim Pieters (University of Antwerp)
      • 94
        Exclusive di-photon and gamma+Z production at the LHC
        We will describe the prospects of measuring exclusive di-photon and Z+gamma events with intact protons at the LHC. Detecting all particles in the final state (the protons being measured in the PPS or AFP detectors respectively in CMS-TOTEM and ATLAS) allow to obtain negligible background and increases the usual sensitivity to quartic photon anomalous couplings at the LHC by about three orders or magnitude. We will also mention the search for Axion Like Particles at high mass using the same processes at the LHC.
        Speaker: Christophe Royon
      • 95
        Recent developments with the APPLgrid project
        Recent developments for the APPLgrid project are presented. These include the ability to reproduce hadron-hadron interaction cross sections with independent parton distributions for each incoming hadron to facilitate QCD analysis of heavy ion data including that from proton-heavy ion collisions. Additional changes to allow the inclusion of a photon density within incident hadrons to aid combined QCD+QED analyses are also reported.
        Speaker: Claire Gwenlan (Oxford)
    • 8:00 AM
    • Plenary Session 2220 A : Chair Avto Kharchilava

      2220 A : Chair Avto Kharchilava

      • 96
        Monte Carlo Overview
        Speaker: Mr Stefan Prestel (Fermilab)
      • 97
        Double parton scattering
        Speaker: Markus Diehl (DESY)
      • 98
        Jet Measurements at the LHC
        Speaker: Christine McLean
    • 10:45 AM
    • Plenary Session 2220 A : Chair Ia Iashvili

      2220 A : Chair Ia Iashvili

      • 99
        New results from Belle II
        New results from Belle II
        Speaker: Vladimir Savinov (University of Pittsburgh)
      • 100
        Higgs Precision
        Speaker: Mr Falko Dulat (ETH Zurich)
      • 101
        Closing Remarks
        Speaker: Prof. Tao Han (Univ. of Pittsburgh)