Description
Conveners:
- Alexander Karlberg (CERN)
- Michael Pitt (CERN)
- Jesse Liu (New York University)
- Silvia Zanoli (University of Oxford)
Contact: eps-hep2025-conveners-T05-l@in2p3.fr
I present analytic results for the scale evolution of the first ten moments of the Parton Distribution Functions (PDFs) through four loops in QCD.
I discuss the evolution of the PDFs to approximate N${}^{3}$LO accuracy, which is constructed by using input from the computed moments and from physical constraints. The N${}^{3}$LO contributions are of the order of $1\%$ or less for...
We investigate the impact of recently computed N3LO corrections to QCD splitting and DIS coefficient functions on global fits of parton distribution functions (PDFs) using the xFitter framework. By comparing fits performed at different perturbative orders, we analyze the modifications introduced to PDFs and their associated uncertainties, incorporating correlated experimental errors....
The top mass is one of the fundamental parameters of the SM and is of key importance for numerous phenomenological applications, thus requiring a precise and accurate determination. In this work, based on the NNPDF4.0 framework, we determine $m_t$ alongside the strong coupling $\alpha_s$, while faithfully propagating experimental and theoretical uncertainties. Traditional approaches often...
An important part of the physics programme of the COMPASS experiment at CERN consists in the measurement of transverse spin and transverse momentum effects in Semi-Inclusive Deep Inelastic Scattering (SIDIS) of high energy muons off unpolarised and transversely polarised nucleons.
In this talk, the most relevant new results on SIDIS off unpolarised protons and transversely polarised deuterons...
Despite the success of perturbative QCD predictions in the high-energy regime, QCD itself remains mysterious at its nominal non-perturbative QCD scale. The LHC offers rich opportunities to probe the core of QCD related questions, by studying minibias events, double parton interactions, small-x and diffractive processes, as well as correlations in hadronization processes. This talk summarizes...
We explore recent developments in the application of small-x resummation to parton distribution functions in the proton, with a particular focus on the gluon sector. In the first part, we provide a concise overview of small-x resummed one-dimensional collinear distributions, emphasizing their interplay with their three-dimensional transverse-momentum-dependent counterparts at both small and...
We calculate several differential distributions for diffractive dijets production in ep โ eโฒjet jet p in the perturbative QCD dipole approach using off diagonal unintegrated gluon distributions (generalized transverse momentum dependent distributions, GTMDs). We concentrate on the contribution from exclusive qqยฏ dijets. Results of our calculations are compared to H1 and ZEUS data, including...
We present an updated determination of $\alpha_s(m_Z)$ based on the global NNPDF4.0 analysis at approximate N$^3$LO QCD mixed with NLO QED accuracy. Consistent results are obtained by means of two independent methodologies, both extensively validated using closure tests. We assess the perturbative convergence of our results, the role of QED corrections and the inclusion of a photon PDF, the...
The strong coupling $\alpha_s$ is the most important parameter of Quantum Chromodynamics (QCD) and therefore it is essential to determine it with high precision. This work presents an improved approach for extracting $\alpha_s$ comparing numerical lattice QCD simulations to the perturbative expansion of the QCD color-singlet static energy. We "R-improve" the $\mathcal{O}(\alpha_s^4)$...
The determination of the QCD coupling, $\alpha_s$, from the analysis of inclusive hadronic tau decays is one of the most precise extractions of this fundamental parameter from experiment. For a long time, the analyses were based on the inclusive spectral functions determined by ALEPH and OPAL. These spectral functions rely on measurements of the dominant decay channels, but necessitated the...
Our work resolves a long-standing problem in particle physics: the inability for theory to agree with the spectrum of heavy-jet mass data, particularly at the Z-pole, leading to unreliable strong-coupling fits and exclusion of this high-quality experimental data. Our key theoretical improvements include high-precision large-log resummation in both the dijet and shoulder regions, a rigorous...
The value of the strong coupling ฮฑS is determined in a comprehensive analysis at next-to-next-to-leading order accuracy in quantum chromodynamics. The analysis uses double-differential cross section measurements from the CMS Collaboration at the CERN LHC of inclusive jet production in proton-proton collisions at centre-of-mass energies of 2.76, 7, 8, and 13 TeV, combined with inclusive...
Due to their large mass, beauty quarks are always produced in hard-scattering processes, and hence their production can be computed with perturbative quantum chromodynamics (pQCD) calculations. The production cross section of beauty hadrons can be theoretically described with the factorisation approach as a convolution of the parton distribution functions of the incoming projectiles, the...
The precision and reach of physics analyses at the LHC is often tied to the performance of hadronic object reconstruction & calibration, with any incremental gains in understanding & reduced uncertainties being impactful on ATLAS results. Recent refinements to the reconstruction and calibration procedures for jets & missing energy by the ATLAS collaboration has resulted in reduced...
Production of multiple jets or bosons plus jets at the LHC offers an unprecedented opportunity to study QCD in the high-energy regime. As experimental precision advances, thorough QCD studies are enabled by measurements of a variety of different observables, including different topological configurations between vector bosons and jets, jet substructure observables, and heavy-flavor jets. In...
Measurements of jet properties (such as the substructure or mass) in proton-proton collisions at the LHC are essential for precise tests of both perturbative and non-perturbative QCD, improving the understanding of proton structure and the strong interaction. In this presentation, we will present the latest measurements with jets performed using data collected by the CMS experiment.
In this talk we present new measurements of inclusive and semi-inclusive jet production in pp collisions, using the high-statistics data sample of Run 3 collected by ALICE. The inclusive jet sample is composed of charged-particle jets, whilst the semi-inclusive sample has the additional constraint that the jets are recoiling from a high-pT charged hadron trigger. For the semi-inclusive sample...
The Koba-Nielsen-Olesen (KNO) scaling of hadron multiplicity distributions, empirically confirmed to hold approximately in $e^+e^-$ collisions and Deep Inelastic Scattering, has been observed to be violated in hadron-hadron collisions. In this work, we show that the universality of KNO scaling can be extended to hadron-hadron collisions when restricted to QCD jets. We present a comprehensive...
The talk addresses the interplay of perturbative and non-perturbative physics in Monte Carlo (MC) generators.
We summarize the studies carried out so far within the TMD parton branching (PB) approach on the extraction of intrinsic transverse momentum (intrinsic-kt) from Drell-Yan (DY) predictions at different center-of-mass energies and in different ranges of invariant mass of the lepton...
We present a comprehensive study of near-threshold structures in the J/\psi J/\psi mass spectrum using the fully reconstructed J/\psi J/\psi \rightarrow 4\mu final state, based on proton-proton collision data at \sqrt{s} = 13 and 13.6 TeV collected by the CMS experiment. With approximately four times more J/\psi pair candidates compared to the previous Run 2 dataset, the combined data sample...
The LHCb experiment has collected the worldโs largest dataset of charmed-hadron decays during LHC Run 1 and Run 2 (2010โ2018), enabling the most precise measurements to date of the production rates and properties of known charmed baryons, as well as the discovery of several previously unobserved states. For Run 3 (2022โ2026), the LHCb detector was significantly upgraded to operate at five...
BESIII has collected 20.3 and 7.33 $fb^{-1}$ of $e^+e^-$ collision data samples at 3.773 and 4.128-4.226 GeV, respectively. This provides a unique opportunity to investigate the non-perturbative nature of QCD in the charm sector.
In this presentation, we will discuss the recent progresses in amplitude analyses and branching fraction measurements of $D_{(s)}\to h h l^+ \nu$ and $h h h l^+ \nu$...
In this presentation, we'll discuss the recent measurements of the
cross-sections for eโบeโป annihilation into hidden charm states at BESIII. These
measurements include: 1) A precise measurement of the eโบeโป โ ฯโบฯโป $h_c$cross section
line shape at center-of-mass energies from 4.009 to 4.950 GeV. A plateau-like shape
between 4.3 and 4.45 GeV, followed by a sharp drop near 4.5 GeV, reveals...
Quarkonium production in high-energy proton-proton (pp) collisions provides a unique probe of both perturbative and non-perturbative aspects of quantum chromodynamics (QCD). Charmonium states, such as the J/ฯ and ฯ(2S), are produced through a two-stage process involving hard parton-parton scatterings followed by non-perturbative hadronization. Precise measurements are essential to constrain...
Precise measurements of charm-hadron production in proton--proton (pp) collisions at the LHC are fundamental to test perturbative QCD-based calculations and to investigate the charm-quark hadronization. Recent measurements in pp collisions show baryon-to-meson ratios significantly larger than those in $\mathrm{e^+e^-}$ collisions, challenging the validity of theoretical calculations based on...
The electron-positron stage of the Future Circular Collider (FCC-ee) is aiming at direct and indirect searches for physics beyond the SM in a new 91-km tunnel at CERN. In addition, the FCC-ee offers unique possibilities for high-precision studies of the strong interaction in the clean environment provided by e$^+$e$^-$ collisions, thanks to its broad span of center-of-mass energies, ranging...
We present recent measurements of event shape variables in proton-proton (pp) collisions with the CMS detector. Event shape variables provide insight into the final-state particle distributions, offering a detailed probe of the perturbative and non-perturbative QCD regimes.
The Breit frame provides a natural frame to analyze lepton--proton scattering events. In this reference frame, the parton model hard interactions between a quark and an exchanged boson defines the coordinate system such that the struck quark is back-scattered along the virtual photon momentum direction. In Quantum Chromodynamics (QCD), higher order perturbative or non-perturbative effects can...
The H1 Collaboration at HERA reports the first measurement of groomed event shape observables in deep inelastic electron-proton scattering (DIS) at $\sqrt{s}=319$ GeV, using data recorded between the years 2003 and 2007 with an integrated luminosity of 351 pb$^{-1}$. Event shapes provide incisive probes of perturbative and non-perturbative QCD. Grooming techniques have been used for jet...
The computation of higher-order corrections to cross-sections relevant at LHC involves the evaluation of phase-space integrals that exhibit soft and collinear divergences. The subtraction of these divergences is a key ingredient to obtain fully-differential predictions for physical observables. We discuss a subtraction method to handle these divergences based on the construction of universal...
Deep-inelastic positron-proton scattering at high momentum transfer $Q^2$ is an ideal place to study QCD effects. The H1 collaboration presents two such studies based on data collected in ep collisions at $Q^2>150$ GeV$^2$. The data are unfolded (corrected for detector effects) using advanced machine learning methods. This results in parallel and unbinned measurements of several observables,...
The LHCb detector, with its unique forward geometry, provides unprecedented kinematic coverage at low Bjorken-x values, down to 10^-6. LHCbโs excellent momentum resolution, vertex reconstruction and particle identification allow precision measurements down to very low hadron transverse momentum. In this talk, recent studies of exclusive vector boson production in proton-proton and heavy ion...
The new results on three-pion Bose-Einstein correlations measured with the sample of proton-proton collisions recorded at the centre-of-mass energy of โs = 7 TeV will be presented, being the first study of three-particle Bose-Einstein correlations measured in the forward region provided by the LHCb detector. The results are interpreted within the core-halo model for the first time in...
Based on the large samples of 10 billion J/ฯ and 2.7 billion ฯ(3686) events collected by the BESIII detector, the recent progresses on baryon spectroscopy, including the amplitude analyses of $ฯ(3686) \to p \bar{p} \pi^0$, $ฯ(3686) \to p \bar{p} \eta$, and $ฯ(3686) \to \Lambda \bar{\Sigma} \pi$, will be presented. The perspectives on the baryon spectroscopy at BESIII will also be discussed.
Leveraging the excellent PID capabilities of the ALICE experiment, coupled with the copious production of ฯ$^0$ mesons and protons at the LHC in pp collisions, ALICE presents the first-ever measurement of the ฯ$^0$โp correlation function as a function of the relative momentum. The data are interpreted employing calculations within the framework of unitarised chiral perturbation theory in a...
Using $(2259.3 \pm 11.1)\times10^{6}$ $\psi(2S)$ events acquired with the BESIII detector, the branching fraction of $\psi(2S)\rightarrow\tau^{+}\tau^{-}$ is measured with improved precision to be
$\mathcal{B}_{\psi(2S)\rightarrow\tau^{+}\tau^{-}}=(3.240~\pm~0.023~\pm~0.081)\times
10^{-3}$, where the first and second uncertainties are statistical and systematic, respectively, which is...
Probing the non-perturbative regime of Quantum Chromodynamics (QCD) remains a critical challenge in hadron spectroscopy, particularly concerning the role of gluonic excitations in shaping the hadronic spectrum. The GlueX experiment at Jefferson Lab is designed to address this challenge through the search for exotic hybrid mesons, states predicted by QCD to include gluonic degrees of freedom...
The Bc meson, the heaviest among known mesons, decays through the weak interaction. Its double-heavy quark content and distinct masses present new challenges and opportunities for testing effective theories with unique decay, spectroscopy and production properties. These features offer valuable insights into heavy-quark dynamics inside hadrons and enhance our understanding of the strong...
The LHCb experiment's exceptional vertex and momentum resolution enables cutting-edge heavy hadron spectroscopy studies. Recent achievements include discovering two new excited $\Xi_{b}$ states in the $\Xi_{b}\pi^{+}\pi^{-}$ final state, observing the rare $J/\psi\rightarrow \mu^{+}\mu^{-}\mu^{+}\mu^{-}$ decay mode, and precision measurements of $\Xi_{b}^{-}$ lifetime and masses of $\chi_{b}$,...
Measurements of the properties of jets initiated by a charm quark represent a valuable tool to investigate the properties of quantum chromodynamics (QCD) processes such as the evolution of the heavy-flavour quark parton shower and hadronisation processes.
Casmir colour effects (different for quarks vs gluons) and mass effects (driven by the dead cone of heavy quarks), impact the properties...
In this talk, I will present our recent developments in MadGraph5_aMC@NLO for elementary-particle production in asymmetric systems, including photoproduction and protonโnucleus collisions. I will also discuss the first implementation of bound-state production, specifically quarkonia, the simplest bound states in QCD. Indeed, we have extended the support of radiative corrections at...
While spin correlations and spin entanglement have been measured for top quarks at the LHC, they remain unexplored for other quark flavors. We propose analysis strategies for measuring spin correlations, entanglement, and Bell nonlocality in $b \bar b$ samples using the partial preservation of the spin information in $\Lambda_b$ baryons from bottom quark fragmentation. We find that certain...
An accurate and efficient simulation of final-state radiation is key for many studies of hadron decays in view of the ever-increasing experimental precision. In this talk, we present a new simulation tool based on the Antenna parton shower, the Vincia generator, which we recently extended to simulate QED radiation from hadrons. As part of this effort, we implemented state-of-the-art tree-level...
