arXiv subjects

Claude Bourrely

Publications and source records attributed to Claude Bourrely.

At least 19 recordsLinked to original sources

arXiv2026

The Quantum Statistical Approach to Parton Distributions updated with recent experimental data

The Quantum Statistical Parton Model (QSPM) has been successful over the years to explain a important set of unpolarized and polarized experimental data on proton parton distribution functions (PDFs). With the advent of the Marathon and SeaQuest experiments, an updated version of the quark PDFs obtained in the framework of QSPM is presented. Moreover, in order to clarify the role of the thermodynamical potentials, the main parameters of the model, we examine the dependence of the nucleon entropy on these potentials. We find that the values of these potentials lead to a maximal value for the nucleon entropy.

hep-ph↗

arXiv2023

Extraction of Kaon Partonic Distribution Functions from Drell-Yan and $J/ψ$ Production Data

We present an analysis to extract kaon parton distribution functions (PDFs) for the first time using meson-induced Drell-Yan and quarkonium production data. Starting from the statistical model first developed for determining the partonic structure of spin-1/2 nucleon and later applied to the spin-0 pion, we have extended this approach to perform a global fit to existing kaon-induced Drell-Yan and $J/ψ$ production data. These data are well described by the statistical model, allowing a first extraction of the kaon PDFs. We find that both the Drell-Yan and the $J/ψ$ data favor a harder valence distribution for strange quark than for up quark in kaon. The kaon gluon distribution is further constrained by the $J/ψ$ production data. In particular, the momentum fraction carried by gluons is found to be similar for pion and kaon.

hep-ph↗

arXiv2022

Pion Partonic Distributions in the Statistical Model from Pion-induced Drell-Yan and $J/Ψ$ Production Data

We present a new analysis to extract pion parton distribution functions (PDFs) within the framework of the statistical model. Starting from the statistical model first developed for the spin-1/2 nucleon, we extend this model to describe the spin-0 pion. Based on a combined fit to both the pion-induced Drell-Yan data and the pion-induced $J/Ψ$ production data, a new set of pion PDFs has been obtained. The inclusion of the $J/Ψ$ production data in the combined fit has provided additional constraints for better determining the gluon distribution in the pion. We also compare the pion PDFs obtained in the statistical model with other existing pion PDFs.

hep-ph↗

arXiv2020

A New Extraction of Pion Parton Distributions in the Statistical Model

We present a new analysis to extract pion's parton distribution functions (PDFs) in the framework of the statistical model. Starting from the statistical model framework first developed for the spin-1/2 nucleon, we apply appropriate modifications taking into account the spin-0 nature of pion and the isospin and charge-conjugation symmetry properties. This results in a significant reduction of the number of parameters compared to a recent work to extract pion's PDFs. Using $π^-$-induced Drell-Yan data to determine the parameters of this statistical model approach, we show that a good description of these experimental data with Next-to-Leading order QCD calculations can be obtained. Good agreement between the calculations and the $π^+/π^-$ Drell-Yan cross section ratio data, not included in the global fit, has confirmed the predictive power of these new pion PDFs.

hep-ph↗

arXiv2019

Flavor symmetry breaking of the nucleon sea in the statistical approach

The flavor structure of the nucleon sea provides unique information to test the statistical parton distributions approach, which imposes strong relations between quark and antiquarks. These properties for unpolarized and helicity distributions have been verified up to now by recent data. We will present here some new results which are a real challenge, also for forthcoming accurate experimental results, mainly in the high Bjorken-$x$ region.

hep-ph↗

arXiv2018

Statistical approach of pion parton distributions from Drell-Yan process

The quantum statistical approach proposed more than one decade ago was used to determine the parton distributions for the proton by considering a large set of accurate Deep Inelastic Scattering experimental results. We propose to extend this work to extract the parton distributions for the pion by using data on lepton pair production from various experiments. This global next-to-leading order QCD analysis leads to a good description of several Drell-Yan $π^- W$ data. The resulting parton distributions are compared with earlier determinations. We will also discuss the difference between nucleon and pion structure in the same approach.

hep-ph↗

arXiv2018

Properties of structure functions from helicity components\\ of light quarks and antiquarks in the statistical model

In the quantum statistical parton distributions approach proposed more than one decade ago to describe the parton structure, new properties are now understood, in particular, the relation between quarks and antiquarks which leads to very specific properties. The simultaneous treatment of unpolarized and polarized Parton Distribution Functions (PDFs) allows a determination of thermodynamical potentials (the master parameters of the model) which drive their behavior and as a consequence those of the structure functions. The existence of a possible relation between the gluon and a $q~\bar q$ pair leads to define a toy model for the unpolarized and polarized gluon. In view of forthcoming experimental results in the large $x$ region specific predictions made by the model are presented.

hep-ph↗

arXiv2017

The landscape of $W^{\pm}$ and $Z$ bosons produced in $pp$ collisions up to LHC energies

We consider a selection of recent experimental results on electroweak $W^{\pm},\,Z$ gauge boson production in $pp$ collisions at BNL RHIC and CERN LHC energies in comparison to prediction of perturbative QCD calculations based on different sets of NLO parton distribution functions including the statistical PDF model known from fits to the DIS data. We show that the current statistical PDF parameterisation (fitted to the DIS data only) underestimates the LHC data on $W^{\pm},\,Z$ gauge boson production cross sections at the NLO by about 20\%. This suggests that there is a need to refit the parameters of the statistical PDF including the latest LHC data.

hep-ph↗

arXiv2017

Properties of the light quarks and antiquarks in the statistical approach

In the quantum statistical parton distributions approach proposed more than one decade ago, one imposes relations between quarks and antiquarks expressions, which lead to very specific properties for the antiquarks. These properties have been verified up to now by recent data and it is a real challenge also for forthcoming experimental results, mainly in the high $x$ region.

hep-ph↗

arXiv2016

Transverse double-spin asymmetries for electroweak gauge-boson production in high-energy polarized $p^{\uparrow} + p^{\uparrow}$ collisions

We consider the production of $W$ and $Z / γ^{*}$ gauge bosons in proton-proton collisions at a center-of-mass energy of $\sqrt{s} = 510 \mbox{GeV}$ available at RHIC at BNL, operating at high luminosity. We stress the importance of measuring the transverse double-spin asymmetries $A_{TT}$, in connection with available transversely polarized beams with a high degree of polarisation. We will discuss some theoretical issues related to the predicted asymmetries. These studies are contrasted to the 2017 RHIC running operation of transversely polarized beams of mid-rapidity $W$ and $Z$ boson production at a center-of-mass energy of $\sqrt{s}=510\,$GeV along with long-term prospects beyond 2020 at RHIC.

hep-ph↗

arXiv2016

New Statistical PDFs: Predictions and Tests up to LHC Energies

The quantum statistical parton distributions approach proposed more than one decade ago is revisited by considering a larger set of recent and accurate Deep Inelastic Scattering experimental results. It enables us to improve the description of the data by means of a new determination of the parton distributions. This global next-to-leading order QCD analysis leads to a good description of several structure functions, involving unpolarized parton distributions and helicity distributions, in a broad range of $x$ and $Q^2$ and in terms of a rather small number of free parameters. There are several challenging issues, in particular the behavior of $\bar d(x) / \bar u(x)$ at large $x$, a possible large positive gluon helicity distribution, etc.. The predictions of this theoretical approach will be tested for single-jet production and charge asymmetry in $W^{\pm}$ production in $\bar p p$ and $p p$ collisions up to LHC energies, using recent data and also for forthcoming experimental results.

hep-ph↗

arXiv2016

The Drell-Yan process as a testing ground for parton distributions up to LHC

The Drell-Yan massive dilepton production in hadron-hadron collisions provides a unique tool, complementary to Deep Inelastic Scattering, for improving our understanding of hadronic substructure and in particular for testing parton distributions. We will consider measurements of the differential and double-differential Drell-Yan cross sections from FNAL Tevatron up to CERN LHC energies and they will be compared to the predictions of perturbative QCD calculations using most recent sets (CT14 and MMHT14) of parton distribution functions, as well as those provided by the statistical approach.

hep-ph↗

arXiv2015

New developments in the statistical approach of parton distributions

The quantum statistical parton distributions approach proposed more than one decade ago is revisited by considering a larger set of recent and accurate Deep Inelastic Scattering experimental results. It enables us to improve the description of the data by means of a new determination of the parton distributions. This global next-to-leading order QCD analysis leads to a good description of several structure functions, involving unpolarized parton distributions and helicity distributions, in terms of a rather small number of free parameters. There are several challenging issues. The predictions of this theoretical approach will be tested for single-jet production and charge asymmetry in $W^{\pm}$ production in $\bar p p$ and $p p$ collisions up to LHC energies, using recent data and also for forthcoming experimental results.

hep-ph↗

arXiv2015

Parton Distribution Functions properties of the statistical model

We show that the parton distribution functions (PDF) described by the statistical model have very interesting physical properties which help to understand the structure of partons. The role of the quark helicity components is emphasized as they represent the building blocks of the PDF. In the model the sign of the polarized quarks PDF comes out in a quite natural way once the thermodynamical potentials with a given helicity are known. Introducing the concept of entropy we study the states madeof |2u + d >, |u +d +s > and $|2\bar u +\bar d >$, for a fixed Q^2, the variation with x shows that the first state has a dominant entropy due to the effect of u quark. We prove that the PDF parameters obtained from experiments give in fact an optimal solution of an entropy equation subject to constraints. We develop a new approach of the polarized gluon density based on a neural model which explains its property, in particular, a large positivity value and an agreement with the positvity constraint. An extension of this neural approach is applied to quarks giving a coherent description of the partons structure.

hep-ph↗

arXiv2015

New developments in the statistical approach of parton distributions: tests and predictions up to LHC energies

The quantum statistical parton distributions approach proposed more than one decade ago is revisited by considering a larger set of recent and accurate Deep Inelastic Scattering experimental results. It enables us to improve the description of the data by means of a new determination of the parton distributions. This global next-to-leading order QCD analysis leads to a good description of several structure functions, involving unpolarized parton distributions and helicity distributions, in a broad range of $x$ and $Q^2$ and in terms of a rather small number of free parameters. There are several challenging issues and in particular the confirmation of a large positive gluon helicity distribution. The predictions of this theoretical approach will be tested for single-jet production and charge asymmetry in $W^{\pm}$ production in $\bar p p$ and $p p$ collisions up to LHC energies, using recent data and also for forthcoming experimental results.

hep-ph↗

arXiv2014

How large is the gluon polarization in the statistical parton distributions approach?

We review the theoretical foundations of the quantum statistical approach to parton distributions and we show that by using some recent experimental results from Deep Inelastic Scattering, we are able to improve the description of the data by means of a new determination of the parton distributions. We will see that a large gluon polarization emerges, giving a significant contribution to the proton spin.

hep-ph↗

arXiv2014

Impact picture for near-forward elastic scattering up to LHC energies

We will recall the main feaatures of an accurate phenomenological model to describe successfully near-forward elastic scattering in a wide energy range, including ISR, SPS and Tevatron colliders. A large step in energy domain is accomplished with the LHC collider, presently running, giving the opportunity to confront the new data with the predictions of our theoretical approach.

hep-ph↗

arXiv2014

New results in the quantum statistical approach to parton distributions

We will describe the quantum statistical approach to parton distributions allowing to obtain simultaneously the unpolarized distributions and the helicity distributions. We will present some recent results, in particular related to the nucleon spin structure in QCD. Future measurements are challenging to check the validity of this novel physical framework.

hep-ph↗