Conveners
WG4: QCD with Heavy Flavours and Hadronic Final States 1
- Pierre-Hugues Beauchemin (Tufts University (US))
- Rene Poncelet (Cambridge University)
- Barbara Antonina Trzeciak (Czech Technical University in Prague)
- Pierre-Hugues Beauchemin (Tufts University (US))
WG4: QCD with Heavy Flavours and Hadronic Final States 2
- Barbara Antonina Trzeciak (Czech Technical University in Prague)
- Rene Poncelet (Cambridge University)
- Pierre-Hugues Beauchemin (Tufts University (US))
- Pierre-Hugues Beauchemin (Tufts University (US))
- Huey-Wen Lin
WG4: QCD with Heavy Flavours and Hadronic Final States 3
- Pierre-Hugues Beauchemin (Tufts University (US))
- Barbara Antonina Trzeciak (Czech Technical University in Prague)
- Rene Poncelet (Cambridge University)
- Pierre-Hugues Beauchemin (Tufts University (US))
WG4: QCD with Heavy Flavours and Hadronic Final States 4
- Huey-Wen Lin
- Ivan Vitev
- Thomas Kurt Gehrmann (University of Zurich (CH))
- Pierre-Hugues Beauchemin (Tufts University (US))
- Pierre-Hugues Beauchemin (Tufts University (US))
- Barbara Antonina Trzeciak (Czech Technical University in Prague)
- Rene Poncelet (Cambridge University)
WG4: QCD with Heavy Flavours and Hadronic Final States 5
- Christophe Royon (University of Kansas)
- Francesco Giuli (CERN)
- Pierre-Hugues Beauchemin (Tufts University (US))
- Rene Poncelet (Cambridge University)
- Barbara Antonina Trzeciak (Czech Technical University in Prague)
- Pierre-Hugues Beauchemin (Tufts University (US))
- Christophe Royon (The University of Kansas (US))
Description
QCD with Heavy Flavours and Hadronic Final States
The production of jets and prompt isolated photons at hadron colliders provides stringent tests of perturbative QCD. We present the latest measurements using proton-proton collision data collected by the ATLAS experiment at √s =13 TeV. Prompt inclusive photon production is measured for two distinct photon isolation cones, R=0.2 and 0.4, as well as for their ratio. The measurement is sensitive...
Photoproduction is an important mode for production of jets and electro-weak particles at lepton--lepton and lepton--hadron colliders and allow for interesting studies of exclusive production at hadron--hadron colliders. In this talk, I will review recent efforts of extending the Sherpa event generator to include calculation of photoproduction for electron and proton beams, including the...
The efficiency of non-local subtraction methods such as qT-subtraction or jettiness subtraction is affected by the size of the power corrections below the slicing cutoff used in the calculation. In this talk I will discuss the scaling of the power corrections for different classes of observables, focussing in particular on transverse observables, which do not depend on the rapidity of QCD radiation.
The production of W/Z bosons in association with heavy flavor jets or hadrons at the LHC is sensitive to the flavor content of the proton and provides an important test of perturbative QCD. We present the production of Z bosons in association with b-tagged large radius jets. The result highlights issues with modelling of additional hadronic activity and provides distinction between...
In this talk, we plan to discuss recent results on third-order (N3LO) perturbative QCD corrections to observables in massive gauge boson production at the LHC. We describe how existing NNLO calculations for vector-boson-plus-jet processes can be utilized to obtain fully differential N3LO predictions for fiducial cross sections in leptonic final states, using the qT subtraction method. The...
The production of single top quarks as well as top-quark pairs in association with electroweak gauge bosons is presented together with the measurement of production asymmetries in ttbar and associated ttbar production. Using the data set collected during run 2 of the LHC (2015-2018, 139/fb of pp collisions at 13 TeV), the ATLAS experiment has observed ttX production, with X=gamma,Z and single...
We review the GENEVA Monte-Carlo framework, that combines three theoretical tools used for QCD precise prediction into a single structure.
It gives fully differential fixed-order calculations up to NNLO via $N$-jettiness subtraction, which are then combined with higher-order resummation in the $0$-jettiness resolution variable. This resummation is carried out to NNLL', matched to the...
The associated production of a Higgs boson with a top-antitop quark pair is a crucial process at the LHC since it allows for a direct measurement of the top-quark Yukawa coupling.
In this talk we present our recent computation of the NNLO QCD corrections to ttH production within qT-subtraction, with an emphasis on the steps needed to apply this formalism to this process and on possible...
We present theoretical calculations of total cross sections and top-quark transverse-momentum and rapidity distributions in the associated production of a top-antitop pair with a photon ($t{\bar t}\gamma$ production). We include complete QCD and electroweak corrections at NLO as well as soft-gluon corrections at approximate NNLO (aNNLO). The aNNLO corrections are very significant, they...
We discuss the reconstruction of target jet and the framework of quantifying its internal substructure. Due to momentum and charge conservation, target and current correlation can be exploited which significantly constrains the event-wide particle distributions. We demonstrate this method using Pythia simulations of electron-proton collisions in the context of identifying the flavor of the...
The substructure of QCD jets has been the subject of intense investigation following the development of infrared and collinear safe clustering algorithms and observables. A particularly illuminating observable to study the radiation patterns of light and heavy partons is the Lund jet plane (LJP), where various types of emissions such as soft-collinear, hard-collinear, and non-perturbative...
Jets are collimated sprays of final-state particles produced from initial high-momentum-transfer partonic (quark/gluon) scatterings in particle collisions. Since jets are multi-scale objects that connect asymptotically free partons to confined hadrons, jet substructure measurements in vacuum can provide insight into the parton evolution and the ensuing non-perturbative hadronization processes....
Various measurements related to the study of hadronic jets substructure in proton collisions at 13 TeV with the CMS experiment are presented. The differential jet production cross section as a function of the jet mass and transverse momentum is shown in events with a Z boson plus jet topology, with and without the soft radiation within a jet removed by a jet grooming algorithm. Measurement of...
The production mechanism of quarkonia in $p$+$p$ collisions involves both the perturbative and non-perturbative QCD processes and is a topic of active investigation. Quarkonium production from Color Singlet Model and Color Octet Mechanism is expected to result in different jet activities, i.e., the number of jets associated with quarkonium creation, due to different numbers of emitted hard...
We present the recent and ongoing developments with respect to the use of machine learning methods in models of hadronization as implemented in general purpose event generators. Specifically we focus on the performance of generative machine learning algorithms in reproducing Pythia-simulated hadronization kinematics and global observables. Finally, we will discuss the inclusion of error...
The LHC produces a vast sample of top quark pairs and single top quarks. Measurements of the inclusive top quark production rates at the LHC have reached a precision of several percent and test advanced Next-to-Next-to-Leading Order predictions in QCD. Differential measurements in several observables are important to test SM predictions and improve Monte Carlo generator predictions. In this...
The remarkably large dataset collected with the ATLAS detector at the highest proton-proton collision energy provided by LHC allows to use the large sample of top quark events to test theoretical predictions with unprecedented precision. Recent highlights are the new measurement of W-boson polarisation in ttbar events single-top quark polarisation, new top-quark mass measurements as well as...
We present the first measurement of two-particle angular correlations of charged particles emitted in high energy $e^+e^-$ annihilation up to $\sqrt{s}=$209~GeV and anti-kT jet energy spectrum and substructure measurements using the archived ALEPH $e^+e^-$ data taken between 1992 and 2000.
The correlation functions are measured as a function of charged particle multiplicity for the first...
The CLAS Collaboration presents a measurement of the nuclear dependence of di-hadron production in deep inelastic scattering off nuclei using the CLAS detector at Jefferson Lab. We report the first measurement of azimuthal correlations in nuclear DIS, and their dependence on kinematic variables such as rapidity separation and the transverse momenta of the two pions. We observe that the...
Mass-dependent quark contributions are of great importance to DIS processes. The simplified-ACOT-$\chi$ scheme includes these effects over a wide range of momentum transfers up to next-to-leading order in QCD. In recent years an improvement in the case of neutral current DIS has been achieved by using zero-mass contributions up to next-to-next-to-leading order (NNLO) with massive phase-space...
Heavy quarkonium production of high transverse momentum ($p_T$) in hadronic collisions can be studied in the QCD factorization formalism in both leading and the first subleading power in $1/p_T$ expansion with heavy quarkonium fragmentation functions (FFs) [1]. The scale evolution of quarkonium FFs enables us to resum logarithmically enhanced corrections $\alpha_s\ln(p_T^2/m^2)$ with heavy...
Centrality-dependent data of hadron and jet attenuation in deep inelastic scattering (DIS) on nuclei can shed new light on the physics of final-state interactions in nuclear matter, including the path-length dependence of in-medium parton shower evolution. Thus-far, such measurements that can disentangle shadowing and energy loss effects on semi-inclusive DIS cross sections have not been...
The lepton-jet momentum imbalance in deep inelastic scattering events offers a useful set of observables for unifying collinear and transverse-momentum-dependent frameworks for describing high energy Quantum Chromodynamics (QCD) interactions. The imbalance in the laboratory frame was measured recently [1] using positron-proton collisions from HERA Run II. With a new machine learning method,...
At leading order in positron-proton collisions, a lepton scatters off a quark through virtual photon exchange, producing a quark jet and scattered lepton in the final state. The total transverse momentum of the system is typically small, however deviations from zero can be attributed to perturbative initial and final state radiations in the form of soft gluon radiation when the transverse...
The radiation pattern within high energy quark and gluon jets (jet substructure) is used extensively as a precision probe of the strong force as well as an environment for optimizing event generators for nearly all tasks in high energy particle and nuclear physics. While there has been major advances in studying jet substructure at hadron colliders, the precision achievable by collisions...
We perform a renormalization group (RG) analysis of cold nuclear matter effect on hadron production in semi-inclusive DIS. We focus on the asymptotic limit where the ratio $t = E/(\mu_D^2 L)\rightarrow \infty$, with $E$, $L$, $\mu_D$ being the energy of the jet, the nuclear size, and the inverse interaction range in cold nuclear matter, while the opacity of the medium remains at order unity....
General-purpose event generators such as Pythia are programs that model complete particle interactions, including the hard process, parton showers, multiparton interactions, hadronization, etc. The objective of these generators is to provide state-of-the-art predictions for high energy collisions, and are essential for bridging the gap between theoretical models and experimental data. Pythia...
Understanding the detailed structure of energy flow within jets, a field known as jet substructure, plays a central role in searches for new physics, and precision studies of QCD. Many applications of jet substructure require an understanding of jets initiated by heavy quarks, whose description has lagged behind remarkable recent progress for massless jets.
In this work we initiate a study of...
The proposed Electron-Ion Collider (EIC) will utilize high-luminosity high-energy electron+proton ($e+p$) and electron+nucleus ($e+A$) collisions to solve several fundamental questions including searching for gluon saturation and studying the proton/nuclear structure. Due to their high masses ($M_{c,b} > \Lambda_{QCD}$), heavy quarks do not transfer into other quarks or gluons once they are...
We present theoretical results for the associated production of a single top quark and a $Z$ boson ($tqZ$ production) at LHC energies. We calculate higher-order corrections from soft-gluon emission for this process. We compute the approximate NNLO (aNNLO) cross section at LHC energies, including uncertainties from scale dependence and from parton distributions. We also calculate the top-quark...
In this talk, I will present NNLO QCD predictions for several differential distributions of B-hadrons in top-pair events at the LHC. In an extension of previous work, the decay of the produced B-hadron to a muon or a J/ψ meson has been incorporated, allowing us to make predictions for distributions involving those decay products as well. Additionally, a new set of B-hadron fragmentation...
The identification of jets containing b-hadrons is key to many physics analyses at the LHC, including measurements involving Higgs bosons or top quarks, and searches for physics beyond the Standard Model. In this contribution, the most recent enhancements in the capability of ATLAS to separate b-jets from jets stemming from lighter quarks will be presented. The improved performance originates...
An intuitive definition of the partonic flavor of a jet in quantum chromodynamics is often only well-defined in the deep ultraviolet, where the strong force becomes a free theory and a jet consists of a single parton. However, measurements are performed in the infrared, where a jet consists of numerous particles and requires an algorithmic procedure
to define their phase space boundaries. In...
Investigating particle production in various collision systems has become in-
strumental in probing non-perturbative contributions to hadron structure and
hadronization. The LHCb spectrometer’s unique geometry among the LHC de-
tectors along with its particle identification and tracking capabilities allow for
new studies in hadron production to identify how said contributions manifest...
{Observables involving heavy quarks can be computed in perturbative QCD in two different approximation schemes: either the quark mass dependence is fully retained, or it is retained only where needed to regulate the collinear singularity. The two schemes have different advantages and drawbacks. In particular, it is known that the structure of large logarithms arising from soft emissions is...
In this talk I will present a recent idea for which one could use the deadcone, a region suppressed by QCD in vacuum to massive kinematic effects, to measure properties of the Quark-Gluon-Plasma, due to in-medium enhancements for massive emitters.
Charmonium is one of the most prominent probes used to investigate and quantify the properties of the quark-gluon plasma (QGP) created in ultra-relativistic heavy-ion collisions. Thanks to its larger size and weaker binding energy, the excited $\psi$(2S) state is expected to be affected differently by the nuclear medium with respect to the J/$\psi$ state, therefore the effects of nuclear...
The production of quarkonium, a bound state of a heavy quark (charm or bottom) and its corresponding antiquark, can be decomposed in a hard-scale perturbative production of the quark-antiquark pair, and its subsequent hadronization into the bound state which can only be described by non-perturbative models, such as NRQCD. In hadronic collisions, the underlying event activity, usually...
Belle II offers unique possibilities for discovering and interpreting exotic multiquark bound states to probe the fundamentals of QCD. This talk presents recent results on a unique data set collected at energies above the $\Upsilon$(4S), including searches for the hidden bottom transition between Y(10750) and $\chi_{bJ}$.
This talk presents recent results about heavy flavor spectroscopy and exotic hadrons at CMS.
Multi-jet rates at hadron colliders provide a unique possibility for probing Quantum Chromodynamics (QCD), the theory of strong interactions. By comparing theory predictions with collider data, one can directly test perturbative QCD, extract fundamental parameters like the strong coupling and search for physics beyond the Standard Model. Recent developments enabled lifting three-jet...
I shall discuss complete calculation of one-loop triple-collinear splitting operators in QCD for all five channels. The results are accurate to second order in dimensional-regularization parameter. This accuracy is sufficient for use in subtraction schemes at next-to-next-to-next-to leading order.
This talk presents recent results about heavy flavor production at CMS.
The production of heavy quarks at the LHC plays a crucial role in the context of precision tests of the Standard Model and the search for new physics. On top of representing a fundamental background for a huge number of processes, heavy quarks can play an important role in constraining Parton Distribution Functions, especially the gluon PDF, in relevant low x regions. Therefore it is essential...
The measurement of exclusive $e^+e^−$ to hadrons processes is a significant part of the physics program of the $BABAR$ experiment, aimed to improve the calculation of the hadronic contribution to the muon $g−2$ and to study the intermediate dynamics of the processes. We present the most recent studies performed on the full data set of about 470 ${\mathrm {fb}}^{−1}$ collected at the PEP-II...
The first measurement of two-particle angular correlations of charged particles emitted in high energy $e^+e^-$ annihilation up to $\sqrt{s} = 209$~GeV is presented, using data collected with the ALEPH detector at LEP between 1992 and 2000. The correlation functions are measured over a broad range of pseudorapidity and full azimuth as a function of charged particle multiplicity for the first...
