Conveners
Strong interactions and Hadron Physics: Strong interactions and Hadron Physics
- Jan Matousek (Charles University (CZ))
- Josu Cantero (IFIC/UV-CSIC (ES))
Strong interactions and Hadron Physics: Strong interactions and Hadron Physics
- Josu Cantero (IFIC/UV-CSIC (ES))
- Katerina Lipka (Deutsches Elektronen-Synchrotron (DE))
Strong interactions and Hadron Physics: Strong interactions and Hadron Physics
- Josu Cantero (IFIC/UV-CSIC (ES))
- Katerina Lipka (Deutsches Elektronen-Synchrotron (DE))
Strong interactions and Hadron Physics: Strong interactions and Hadron Physics
- Katerina Lipka (Deutsches Elektronen-Synchrotron (DE))
- Josu Cantero (IFIC/UV-CSIC (ES))
Strong interactions and Hadron Physics: Strong interactions and Hadron Physics
- Raffaele Del Grande (Technische Universitaet Muenchen (DE))
- Liupan An (Peking University (CN))
Strong interactions and Hadron Physics: Strong interactions and Hadron Physics
- Liupan An (Peking University (CN))
- Jan Matousek (Charles University (CZ))
Strong interactions and Hadron Physics: Strong interactions and Hadron Physics
- Raffaele Del Grande (Technische Universitaet Muenchen (DE))
- Valerio Bertone (C.E.A. Paris-Saclay)
Strong interactions and Hadron Physics: Strong interactions and Hadron Physics
- Raffaele Del Grande (Technische Universitaet Muenchen (DE))
- Katerina Lipka (Deutsches Elektronen-Synchrotron (DE))
Strong interactions and Hadron Physics: Strong interactions and Hadron Physics
- Liupan An (Peking University (CN))
- Valerio Bertone (C.E.A. Paris-Saclay)
Strong interactions and Hadron Physics: Strong interactions and Hadron Physics
- Jan Matousek (Charles University (CZ))
- Valerio Bertone (C.E.A. Paris-Saclay)
Strong interactions and Hadron Physics: Strong interactions and Hadron Physics
- Valerio Bertone (C.E.A. Paris-Saclay)
- Jan Matousek (Charles University (CZ))
Strong interactions and Hadron Physics: Strong interactions and Hadron Physics
- Jan Matousek (Charles University (CZ))
- Raffaele Del Grande (Technische Universitaet Muenchen (DE))
In this talk, recent measurements of distributions sensitive to the underlying event, the hadronic activity observed in relationship with the hard scattering in the event, by the ATLAS experiment are presented. Underlying event observables like the average particle multiplicity and the transverse momentum sum are measured for Kaons as Lambda baryons as a function of the leading track-jet and...
Inclusive event shape distributions, as well as event shapes as a function of charge particle multiplicity are extracted from CMS low-pileup and compared with predictions from various generators. Multi-dimensional unfolded distributions are provided, along with their correlations, using state-of-the-art machine-learning unfolding methods.
We will present results on exclusive production processes in CMS, including the production of charged hadron or lepton pairs. To select these signatures, some analyses use intact protons tagged in the TOTEM roman pot detectors.
The production of W/Z bosons in association with light or 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. In this talk, measurements by the ATLAS experiment probing the charm and beauty content of the proton are presented. Inclusive and differential cross-sections of Z boson production with at least...
The study of the associated production of vector bosons and jets constitutes an excellent environment to check numerous QCD predictions. Total and differential cross sections of vector bosons produced in association with jets have been studied in pp collisions using CMS data. Differential distributions as a function of a broad range of kinematical observables are measured and compared with...
Jet substructure measurements, using the distribution of final state hadrons, provide insight into partonic shower and hadronisation. Observables for such measurements include the transverse momentum ($j_\mathrm{T}$) and longitudinal momentum fraction ($z$) of jet constituent particles. ALICE has recently measured the $j_\mathrm{T}$ distributions of the jet fragments in proton-proton and...
Hadronic object reconstruction is one of the most promising settings for cutting-edge machine learning and artificial intelligence algorithms at the LHC. In this contribution, highlights of ML/AI applications by ATLAS to particle and boosted-object identification, MET reconstruction and other tasks will be presented.
The Energy-Energy Correlator is an observable that explores the angular correlations of energy depositions in detectors at high-energy collider facilities. It has been extensively studied in the context of precision QCD. In this presentation, I will discuss our recent work on the energy-energy correlator in the context of Deep Inelastic Scattering. In the limit where the energy emissions are...
The radiation pattern within high energy quark and gluon jets (jet substructure) is used as a precision probe of QCD and for optimizing event generators. As compared to hadron colliders, the precision achievable by collisions involving electrons is superior, as most of the complications from hadron colliders are absent. Therefore jets are analyzed in deep inelastic scattering events, recorded...
The H1 Collaboration at HERA reports the first measurement of groomed event shapes in deep inelastic ep scattering (DIS) at $\sqrt{s} = 319$ GeV, using data recorded between 2003 and 2007 with an integrated luminosity of $351.1\pm 9.5$ pb$^{โ1}$. Event shapes in DIS collisions provide incisive probes of perturbative and non-perturbative QCD, and recently developed grooming techniques...
The H1 Collaboration reports the first measurement of the 1-jettiness event shape observable $\tau_{1}^{b}$ in neutral-current deep-inelastic electron-proton scattering. The analysis is based on data recorded in 2003-2007 by the H1 detector at the HERA collider for ep collisions at sqrt(s)=319 GeV, with integrated luminosity of 351.1 pb$^{-1}$. The observable $\tau_{1}^{b}$ is equivalent to a...
Measurements of the substructure of jets are presented using 140 fb-1 of proton-proton collisions with sqrt(s)=13 TeV center-of-mass energy recorded with the ATLAS detector at CERN Large Hadron Collider. Various results are presented including the measurement of non-perturbative track functions, or, the ratio of a jet transverse momentum carried by its charged constituents to its complete...
This talk presents the ALICE measurements of $\pi^{0}$, $\eta$, and $\omega$ meson production in pp collisions at 13 TeV. The results are given for several multiplicity classes, each for an unprecedented $p_{\rm T}$ coverage. Furthermore, the measurement of $\pi^{0}$ and $\eta$ mesons inside of jets will be shown.
ALICE measurements of neutral meson production in pp, p+Pb and Pb+Pb...
Jet substructure measurements sensitive to the strong coupling are presented, namely the primary Lund jet plane and the energy-energy correlated. The measurements are motivated by their sensitivity to the strong coupling and present interesting experimental properties.
The coupling constant of the strong force is determined from the transverse-momentum distribution of Z bosons produced in 8 TeV proton-proton collisions. The Z-boson cross sections are measured in the full phase space of the decay leptons. The analysis is based on predictions evaluated at third order in perturbative QCD, supplemented by the resummation of logarithmically enhanced contributions...
A new measurement of inclusive-jet cross sections in the Breit frame in neutral current deep inelastic scattering using the ZEUS detector at the HERA collider is presented. The data were taken at a centre-of-mass energy of 318 GeV and correspond to an integrated luminosity of 347 pb-1. Massless jets, reconstructed using the kt-algorithm in the Breit reference frame, have been measured as a...
The production of jets at hadron colliders provides stringent tests of perturbative QCD. The latest measurements by the ATLAS experiment are presented in this talk, using multijet events produced in the proton-proton collision data at sqrt(s) = 13 TeV delivered by the LHC. Jet cross-section ratios between inclusive bins of jet multiplicity are measured differentially in variables that are...
A vast program of measurements of the strong coupling constant alpha_S is being undertaken by CMS. These measurements exploit several QCD dominated processes that are sensitive to alpha_S, and present different theoretical and experimental challenges. A review of the current public results and perspective is given.
The jet cross sections and azimuthal correlations among jets with large transverse momentum at CMS are measured, the results were compared to theory predictions, and the strong coupling constant was extracted.
We extend the existing NNPDF4.0 sets of parton distributions (PDFs) to approximate next-to-next-to-next-to-leading (aN3LO).
We construct an approximation to the N3LO splitting functions that includes all available partial information from both ๏ฌxed-order computations and from small- and large-x resummation, and estimate the uncertainty on this approximation. We include known N3LO corrections...
The CERN Future Circular Collider (FCC) is a post-LHC project aiming at direct and indirect searches for physics beyond the SM in a new 91 km tunnel. In addition, the FCC-ee offers unique possibilities for high-precision studies of the strong interaction in the clean e+e- environment, thanks to its broad span of c.m. energies from the Z pole to the top-pair threshold, and its huge integrated...
The Large Hadron-electron Collider and the Future Circular Collider in electron-hadron mode [1] will make possible the study of DIS in the TeV regime providing electron-proton (nucleus) collisions with per nucleon instantaneous luminosities around $10^{34}$ ($10^{33}$) cm$^{โ2}$s$^{โ1}$. Following the renewal of the CERN mandate, in this talk we present the status of the studies on proton and...
We evaluate the unintegrated gluon distribution of the proton starting from a parametrization of the color dipole cross section including Dokshitzer--Gribov--Lipatov--Altarelli--Parisi (DGLAP) evolution and saturation effects. To this end, we perform the Fourier-Bessel transform of $\sigma(x,r)/\alpha(r)$. At large transverse momentum of gluons we match the so-obtained distribution to the...
The need of percent precision in high energy physics requires the inclusion of QED effects in theoretical predictions, for example like the contributions coming from photon initiated processes. It is trivial then, to correctly determine the photon content of the proton.
In this work, we extend the NNPDF4.0 NNLO determination of parton distribution functions (PDFs) with a photon PDF,...
We present recent results based on the IR-improvement of unintegrable singularities in the infrared regime via amplitude-based resummation in $QED\times QCD โ SU(2)_L \times U_1 \times SU(3)^c$. In the context of precision LHC/FCC physics, we focus on specific examples, such as the removal of QED contamination in PDFโs evolved from data at $Q_0^2\sim 2 GeV^2$ and used in evaluating precision...
We measure proton structure parameters sensitive primarily to valence quarks using $8.6~{\rm fb}^{โ1}$ of data collected by the D0 detector in $\sqrt{s} = 1.96~{\rm TeV}$ ${\rm p\bar{p}}$ collisions at the Fermilab Tevatron. We exploit the property of the forward-backward asymmetry in dilepton events to be factorized into distinct structure parameters and electroweak quark-level asymmetries....
The internal motion of partons has been studied through its impact on
very low transverse momentum spectra of Drell Yan pairs
created in hadron-hadron collisions at NLO using the Parton Branching
(PB) Method which describes the evolution of transverse momentum
dependent (TMD) parton distributions. The main focus is on studying the
dependence of the intrinsic transverse momentum of partons...
Event classifiers based on the charged-particle multiplicity have been extensively used in pp collisions at the LHC. However, one drawback of the multiplicity-based event classifiers is that requiring a high charged-particle multiplicity biases the sample towards hard processes. These biases blur the effects of multi-parton interactions (MPI) and make it difficult to pinpoint the origins of...
Recent CMS results on production of open heavy flavor hadrons and quarkonia in pp collisions are discussed. The measurements are performed with data collected in pp collisions at sqrt(s)=13 TeV between 2016 and 2018.
Recent ATLAS results on heavy-flavour hadron production are presented, including production of open charm and beauty, charmonia, and associated production of $J/\psi$ with $t\bar t$.
LHCb functions as a spectrometer targeting the forward region of proton-proton collisions, focusing on a pseudo-rapidity range between 2 and 5. Due to the scarcity of background events in the high mass region, its precise reconstruction capabilities and an optimized trigger system, LHCb offers an optimal environment for probing (exotic) Higgs decays. In this talk, we discuss the latest...
Jet substructure observables are sensitive to the effects arising from the mass of quarks produced by QCD hard-scattering interactions. In particular, QCD predicts the suppression of collinear emission around a massive quark, the so-called dead-cone effect, recently observed by the ALICE collaboration at the LHC.
In this talk we discuss how the quark mass affects the theoretical...
In order to obtain total charm cross sections in hadron-hadron collisions, measured fiducial cross sections need to be extrapolated including the treatment of charm fragmentation non-universality effects which have recently been reported by the LHC experiments. For this, a novel phenomenological approach [1] was introduced with a theory-inspired extrapolation function which is constrained by...
Measurements of beauty-hadron production in pp collisions provide a fundamental tool for testing perturbative QCD calculations. Studies in p--Pb collisions allow us to shed light on the role of cold nuclear matter effects on beauty production and their impact on beauty-quark hadronisation.
In this presentation, the final results on the production of charm mesons and baryons from...
Measurements of charm-strange meson and charm-baryon production in pp and heavy-ion collisions at the LHC are fundamental to investigate the charm-quark hadronisation across collision systems.
In this contribution, the final results of the ALICE Collaboration on the production of strange ($\mathrm{D_s}^+$ , $\Xi_\mathrm{c}^{0,+}$, $\Omega_\mathrm{c}^0$) and non-strange ($\mathrm{D}^0$ ,...
Fragmentation functions (FFs) are typically parametrised exploiting measurements performed in $\mathrm{e^+e^-}$ and $\mathrm{e^-p}$ collisions, under the assumption of universality across collision systems. Measurements of charmed-hadron yields in pp collisions at LHC have proved that the fragmentation of heavy quarks differ in hadronic and leptonic collisions.
In this talk, we present...
Polarization and spin correlations have been explored very little for quarks other than the top. Utilizing the partial preservation of the quark's spin information in baryons in the jet produced by the quark, we examine possible analysis strategies for ATLAS and CMS to measure the quark polarization and spin correlations in $pp\to q\bar{q}$ processes. We find polarization measurements for the...
We discuss production of $D$ mesons in $p\!-\!H\!e$ and $p\!-\!N\!e$ collisions at the LHCb in the fixed-target mode. We explain how the LHCb data may put constraints on the intrinsic charm (IC) component in the nucleon. We show that there is a possible scenario in which the traditional components are insufficient to describe the LHCb data, especially for backward rapidities and large meson...
The azimuthal correlation angle, $\Delta\phi$, between the scattered lepton and the leading jet in deep inelastic $ep$ scattering at HERA has been studied using HERA II data collected with the ZEUS detector. Differential cross sections, $d\sigma/d\Delta\phi$, are presented for the first time as a function of the azimuthal correlation angle in various ranges of the jet transverse momentum...
The study of charmonium production in proton-proton collisions provide an excellent probe of QCD, as it involves both the perturbative and non-perturbative regime. At the LHC, charmonia are produced via hadroproduction in proton-proton collision vertex or from b-hadron decays. In both cases, they can also originate from an intermediate excited charmonium, which is required to be understood to...
We investigate the challenges posed by non-global logarithms in analyzing the jet mass observable within the context of Z+jet production, employing jet grooming techniques. Their presence is obvious even if the jet clustering effects tend to reduce their contribution. Our approach involves both an analytical fixed-order calculation, extending up to second order in the coupling, and an...
We present for the first time a revised study of charmonium production in nuclear ultra-peripheral collisions (UPC) based on a rigorous Green's function formalism. Such a formalism allows to incorporate properly effects of the color transparency, as well as the quantum coherence inherent in the higher twist quark shadowing related to the $Q\bar Q$ Fock component of the photon. The significance...
The exclusive photoproduction reactions ฮณp โ J/ฯ(1S)p and ฮณp โ ฯ(2S)p have been measured at an ep centre-of-mass energy of 318 GeV with the ZEUS detector at HERA using an integrated luminosity of 373 pb$^{โ1}$. The measurement was made in the kinematic range 30 < W < 180 GeV, Q$^2$ < 1 GeV2 and |t| < 1 GeV$^2$, where W is the photon-proton centre-of-mass energy, Q$^2$ is the photon virtuality...
We investigate the exclusive photoproduction of J/psi mesons in
ultraperipheral heavy-ion collisions in the color dipole approach. We
use the color dipole formulation of Glauber-Gribov theory to calculate
the diffractive amplitude on the nuclear target.
We discuss the role of $c \bar c g$-Fock states, which can be understood
in terms of the shadowing of the nuclear gluon distribution. We...
We present a study of both inclusive and diffractive neutrino-nucleus scattering in the framework of the QCD dipole model and Color Glass Condensate effective field theory. This study fills the gap in this topic, as diffractive production in such process is investigated for the first time. We show that although the effect of gluon saturation is small, there are some of its signatures which...
In this study, we revisit the extraction of parton-to-$K^0_S$ hadron fragmentation functions (FFs)focusing on both next-to-leading-order(NLO) and next-to-next-to-leading-order (NNLO) accuracies.
Our approach involves the analysis of single inclusive electron-positron annihilation (SIA) data, marking the first incorporation of the most recent experimental data from BESIII. Employing the...
Fragmentation Functions (FF) play a crucial role in the description of the hadronization process. We report the measurements of normalized differential cross sections of inclusive hadron production as a function of hadron momentum at six energy points with $q^2$ transfer from 5 to 13 GeV$^2$ at BESIII.
The causal view of hadron formation allows to establish a simple quantization scheme describing mass spectra of light hadrons. The resulting model predicts a multitude of observable effects. The talk contains a short introduction to the model followed by the comparison of its predictions with recent LHC measurements.
As the $\phi$ meson is composed of a pair of strange-antistrange quarks, it puts implicit constraints on modelling the hadronization procedure itself. Perturbative QCD inspired models, such as PYTHIA 8, describe hadronization through parton showers where strangeness is conserved on a quark-by-quark basis. In contrast, quark-gluon plasma inspired models, such as EPOS-LHC and EPOS4, model...
Experimental data on the interaction between vector mesons and nucleons are a crucial input for understanding the pattern of in-medium chiral symmetry restoration (CSR) and the dynamically generated excited N($\Delta$) states. However, accessing these interactions is hampered by the short-lived nature of vector mesons, making conventional scattering experiments unfeasible. Leveraging the...
The composition of the innermost region of neutron stars is unknown, and the possible appearance of QCD axions has recently been proposed to help understand this puzzle. The properties of axions at high baryon densities can be related to the in-medium properties of pions, which are accessible in pp collisions at the LHC. Here, the emission of multiple hadrons helps to mimic high densities due...
In the last decade, several resonances in the mass range 900-2000 MeV/$c^{2}$ (e.g. $f_{0}$(980) and $f_{1}$(1285)) have been proposed to have exotic quark compositions. Theory predicts it can be a linear composition of two u and d quarks or can have hidden strangeness to form tetra-quark hadrons or hadrons with a hybrid structure. The excellent particle identification capabilities of the...
We show that the masses of pion and its excited states as well as the pion decay constant, charge radius, electromagnetic form factor and photon-to-pion transition form factor can be simultaneously described by the holographic light-front QCD for the transverse dynamics augmented by the 't Hooft equation governing the longitudinal dynamics. We point out that this formalism satisfy the GMOR constraint.
Bound state constituents move in the instantaneous potential generated by their companions. QED and QCD have instantaneous potentials when the gauge is fixed over all space at an instant of time (eg., A^0=0). Thus the Schrรถdinger equation can be generalised to relativistic motion [1].
The QCD potential felt by a quark or gluon can be non-vanishing at spatial infinity for color singlet...
For fifty years, the standard model of particle physics has been hugely successful in describing subatomic phenomena. Recently, this statement appeared to be contradicted by the strong disagreement between the recent measurement of the anomalous magnetic moment of the muon, $a_\mu$, and the reference standard-model prediction for that quantity. Such a large discrepancy should signal the...
The radiative decays of $J/\psi$ provide a gluon-rich environment and are therefore regarded as one of the most promising hunting grounds for glueballs. Using the world's largest samples of $J/\psi$ events produced in $e^+e^-$ annihilation, BESIII performed the first measurements of the quantum numbers of the $X(2370)$ particle, along with its mass, production, and decay properties, and...
At BESIII, the lineshapes of $e^+e^- \to \phi \pi\pi$, $\omega \pi\pi$, $\phi \pi^0$, $K_sK_L \pi^0$, $\eta \pi \pi$ and $\omega \eta^{'}$ are
measured from 2.0 to 3.08 GeV, where resonant structures are observed in these processes. These results provide important information on light vector mesons (i.e. excited $\rho$, $\omega$ and $\phi$) in the energy regions above 2 GeV.
In electron-positron annihilation, the process $e^+e^- \to \chi_{c1}$ can occur via the production of two virtual photons or through neutral current, therefore being suppressed with respect to the normal annihilation process via one virtual photon. Using a dedicated scan sample around the $\chi_{c1}$ mass, the direct production of $\chi_{c1}$ has been established for the first time. This...
This talk will present four recent measurements conducted by BESIII, focusing on the cross-sections of electron-positron annihilation into open-charm and hidden-charm final states within the center-of-mass energies ranging from 3.80 to 4.95 GeV. The open charm final states include $e^+ e^- \to D \bar{D}$ and $D_s^+ D_s^-$, revealing abundant structures in their cross-section line shapes. The...
Studying the properties and behavior of pentaquarks deepens our understanding of quantum chromodynamics (QCD) and the strong interactions. The LHCb experiment, with a large heavy-flavor dataset and detector performance optimized for beauty and charm hadron studies, is uniquely positioned to explore the properties of heavy-flavor pentaquark states. This talk highlights the latest advancements...
Since the obervation of the X(3872), a large number of exotic tetraquark candidates has been observed in the past 20 years. Moreover, some of these hadrons suggest an explicit exotic internal structure: charged, open-flavour, doubly heavy-flavour, full heavy-flavour states have enriched the field of exotic spectroscopy along with an increasing interest from the theory community. These states...
Recent ATLAS results on exotic hadron spectroscopy will be presented, including studies of exotic tetraquarks using various final states and searches for exotics in $\Upsilon+2\mu$ channel
The production mechanism of (anti)nuclei in ultrarelativistic hadronic collisions is under intense debate in the scientific community. Two successful models used for the description of the experimental measurements are the statistical hadronisation model and the coalescence approach. In the latter, multi-baryon states are assumed to be formed by coalescence of baryons that are close in...
(Anti)hypernuclei are among the most promising probes to study the production mechanism of light nuclei in high-energy hadronic collisions. According to coalescence, the production of $\mathrm{^{3}_{\Lambda} H}$, $\mathrm{^{4}_{\Lambda} H}$, and $\mathrm{^{4}_{\Lambda} He}$ in small colliding systems (pp and pโPb) is extremely sensitive to their internal wave function, while in the Statistical...
Experimental results on the electromagnetic form factors are very useful to constrain the QCD-based theoretical models. The electron-positron collider experiments are powerful tools to study the EMFFs of various baryons in time-like region via energy scan or ISR-return methods. We will report recent progress of baryon EMFFs measurements in time-like region at BESIII, including the EMFFs of the...
We will discuss the light-front formulation of quarkonium $\gamma^* \gamma$ transition form factors for $J^{PC} = 2^{++}$ meson states. We will present $\gamma^* \gamma \to \chi_{c2}$ transition amplitudes and the pertinent helicity form factors. We show the results for the two-photon decay width of $\chi_{c2}$ as well as three independent $\gamma^* \gamma$ transition form factors of...
We present a first-principles lattice QCD calculation of the local form factors describing the $B_{s}\to \mu^{+}\mu^{-}\gamma$ decay. We focus on the region of large di-muon invariant masses $\sqrt{q^{2}} \gtrsim 4.2~{\rm GeV}$, where the contributions from the four-quarks operators in the effective weak Hamiltonian (which are neglected at present) are expected to be small. We use our results...
The rare radiative $K^+\to\pi^+\ell^+\ell^-$ decays ($\ell=e,\mu$) provide experimental access to the $K^+\to\pi^+\gamma^*$ transition. The relevant form factor is conventionally written in terms of two hadronic parameters, $a_+$ and $b_+$, which are being measured by NA62 in both electron and muon channels. Comparing the two channels allows for a stringent test of lepton-flavor universality....
2-color QCD (SU(2) gauge theory coupled to fundamental fermions) has several novel features: for instance, enhanced Pauli-Gursey symmetry yields degeneracies between mesons and di/tetra-quark states. The quantum mechanical matrix model provides a simplified platform to directly probe the properties of low-energy (spin-0 and spin-1) hadrons. Using variational calculation, we numerically obtain...
COMPASS is the longest-running experiment at CERN, having performed a series of data takings from 2002 to 2022, spanning a record-breaking 20 years.
One of the objectives of the experiment's broad physics program was to perform semi-inclusive measurements of target spin-dependent asymmetries in (di-)hadron production in DIS using 160 GeV muons and polarized targets.
These measurements...
It has been proposed that at small Bjorken x, or equivalently at high energy, hadrons represent maximally entangled states of quarks and gluons. This conjecture is in accord with experimental data from the electron-proton collider HERA at the smallest accessible x. In this Letter, we propose to study the onset of the maximal entanglement inside the proton using Diffractive Deep Inelastic...
Studies of the transverse-spin dependent azimuthal asymmetries in the Drell-Yan process permit to access the spin-dependent structure of the nucleon and in particular to test the limited universality of its transverse-momentum dependent parton distributions, which are known from deep inelastic scattering.
In 2015 and 2018 the COMPASS Collaboration at CERN performed measurements of the...
Chiral symmetry constrains QCD properties in large magnetic fields $e B \sim m_\pi^2$, thereby providing stringent model-independent tests for lattice QCD and hadronic models. As examples of magnetic-field dependent observables calculated with chiral perturbation theory, we exhibit the finite-volume dependence of the pressure anisotropy and magnetization, as well as detail how finite-volume...
A measurement of additional radiation in $e^+e^-\to\mu^+\mu^-\gamma$ and $e^+e^-\to\pi^+\pi^-\gamma$ initial-state-radiation events is presented using the full $BABAR$ data sample. For the first time results are presented at next-to- and next-to-next-to-leading order, with one and two additional photons, respectively, for radiation from the initial and final states. The comparison with the...
We consider extensions of the soft-gluon effective coupling that generalize the Catani-Marchesini-Webber (CMW) coupling in the context of soft-gluon resummation beyond the next-to-leading logarithmic accuracy. Starting from the probability density of correlated soft emission in d dimensions we introduce a class of soft couplings relevant for resummed QCD calculations of hard-scattering...
Hard exclusive meson production and deeply virtual Compton scattering are common processes to constrain generalised parton distributions. The measurement of exclusive reactions, notably the exclusive $\pi^0$ production, were conducted at COMPASS in 2016 and 2017 using the 160 GeV/$c$ muon beam scattering off a 2.5~m long liquid hydrogen target equipped with time-of-flight detector to record...
We present a novel strategy based on the step-scaling technique to study non-perturbatively thermal QCD up to very high temperatures. As a first concrete application, we compute the meson and baryonic screening masses with a precision of a few per mille in the temperature range from approximately 1 GeV up to the electroweak scale in the theory with three massless quarks. We observe a clear...
We investigate the role of elastic and inelastic (radiative) processes in the strongly interacting quark-gluon plasma (sQGP) within the effective dynamical quasi-particle model (DQPM) constructed for the description of non-perturbative QCD phenomena of the strongly interacting quark-gluon plasma (sQGP) in line with the lattice QCD equation-of-state.
We present the results for the:
1)...
We calculate differential distributions for diffractive dijets production in $e p \to e' p$ $jet$ $jet$ using off diagonal unintegrated gluon distributions (GTMDs). Different models are used.
We concentrate on the contribution of exclusive $q \bar q$ dijets.
Results of our calculations are compared to H1 and ZEUS data. In general, except of one GTMD, our results are below the HERA data....
We evaluate the cross section for diffractive bremsstrahlung of a single photon in the $pp \to pp \gamma$ reaction at high energies and at forward photon rapidities. Several differential distributions, for instance, the rapidity, the absolute value of the transverse momentum, and the energy of the photon are presented. We discuss also azimuthal correlations between outgoing particles. We...
We present our results for azimuthal decorrelation of a vector boson and jet in proton-proton collisions. We show that using a recoil-free jet definition reduces the sensitivity to contamination from soft radiation and simplifies our calculation by eliminating non-global logarithms. Specifically, we consider the $p_T^n$ recombination scheme, as well as the $n\to \infty$ limit, known as the...
Understanding the cancellation of ultraviolet and infrared singularities in perturbative quantum field theory is of central importance for the development and automation of various theoretical tools that make accurate predictions for observables at high-energy colliders. The loop-tree duality aims to find an efficient solution by treating loop and tree-level contributions under the same foot...
