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Parton

About: Parton is a research topic. Over the lifetime, 13484 publications have been published within this topic receiving 368877 citations.


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Journal ArticleDOI
TL;DR: This work reviews the recent developments in the field of generalized parton distributions and deeply virtual Compton scattering in the valence region and examines several state-of-the-art parametrizations of GPDs.
Abstract: This work reviews the recent developments in the field of Generalized Parton Distributions (GPDs) and Deeply virtual Compton scattering in the valence region, which aim at extracting the quark structure of the nucleon. We discuss the constraints which the present generation of measurements provide on GPDs, and examine several state-of-the-art parametrizations of GPDs. Future directions in this active field are discussed.

108 citations

Journal ArticleDOI
TL;DR: In this article, it was shown that perturbative saturation leads to transverse momentum broadening in the spectrum of partons produced in hadronic collisions, and that this broadening has a simple interpretation as the parton level Cronin effect for systems in which saturation is generated by the "tree level" Glauber-Mueller mechanism.
Abstract: We note that the phenomenon of perturbative saturation leads to transverse momentum broadening in the spectrum of partons produced in hadronic collisions. This broadening has a simple interpretation as the parton level Cronin effect for systems in which saturation is generated by the "tree level" Glauber-Mueller mechanism. For systems where the broadening results form the nonlinear QCD evolution to high energy, the presence or absence of the Cronin effect depends crucially on the quantitative behavior of the gluon distribution functions at transverse momenta k(t) outside the so called scaling window. We discuss the relation of this phenomenon to the recent analysis by Kharzeev, Levin, and McLerran of the momentum and centrality dependence of particle production in nucleus-nucleus collisions at BNL RHIC.

108 citations

Journal ArticleDOI
TL;DR: In this paper, a direct matching from the regularization independent momentum subtraction scheme (RI/MOM) to the collinear parton distribution was carried out for the quasi-PDF and PDF, determining the non-singlet quark matching coefficient at next to leading order in perturbation theory.
Abstract: The quasiparton distribution is a spatial correlation of quarks or gluons along the $z$ direction in a moving nucleon which enables direct lattice calculations of parton distribution functions. It can be defined with a nonperturbative renormalization in a regularization independent momentum subtraction scheme (RI/MOM), which can then be perturbatively related to the collinear parton distribution in the $\overline{\mathrm{MS}}$ scheme. Here we carry out a direct matching from the RI/MOM scheme for the quasi-PDF to the $\overline{\mathrm{MS}}$ PDF, determining the non-singlet quark matching coefficient at next-to-leading order in perturbation theory. We find that the RI/MOM matching coefficient is insensitive to the ultraviolet region of convolution integral, exhibits improved perturbative convergence when converting between the quasi-PDF and PDF, and is consistent with a quasi-PDF that vanishes in the unphysical region as the proton momentum ${P}^{z}\ensuremath{\rightarrow}\ensuremath{\infty}$, unlike other schemes. This direct approach therefore has the potential to improve the accuracy for converting quasidistribution lattice calculations to collinear distributions.

108 citations

Journal ArticleDOI
TL;DR: In this paper, the scale dependence of the ratios of parton distributions in a proton of a nucleus and in the free proton was studied within the framework of the lowest order leading-twist DGLAP evolution.
Abstract: The scale dependence of the ratios of parton distributions in a proton of a nucleus $A$ and in the free proton, $R_i^A(x,Q^2)=f_{i/A}(x,Q^2)/f_i(x,Q^2)$, is studied within the framework of the lowest order leading-twist DGLAP evolution. By evolving the initial nuclear distributions obtained with the GRV-LO and CTEQ4L sets at a scale $Q_0^2$, we show that the ratios $R_i^A(x,Q^2)$ are only moderately sensitive to the choice of a specific modern set of free parton distributions. We propose that to a good first approximation, this parton distribution set-dependence of the nuclear ratios $R_i^A(x,Q^2)$ can be neglected in practical applications. With this result, we offer a numerical parametrization of $R_i^A(x,Q^2)$ for all parton flavours $i$ in any $A>2$, and at any $10^{-6}\le x \le 1$ and any $Q^2\ge 2.25$ GeV$^2$ for computing cross sections of hard processes in nuclear collisions.

108 citations

Journal ArticleDOI
TL;DR: In this paper, the main splitting functions for the evolution of longitudinally polarized parton densi ties of hadrons in perturbative QCD were derived by extending all Mellin-N calculations to the structure function g 1 in electromagnetic deep-inelastic scattering.

108 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023384
2022897
2021410
2020423
2019472
2018424