Global study of nuclear modifications on parton distribution functions

TL;DR

This paper presents a comprehensive global analysis of nuclear modifications to parton distribution functions, introducing two datasets and modeling complex nuclear effects with minimal parameters, advancing understanding of nuclear QCD phenomena.

Contribution

It provides the first global fit of nuclear parton distribution functions incorporating nonlinear QCD corrections and models nuclear effects with only two free parameters.

Findings

Two datasets of nuclear modification factors are provided.

Nuclear gluon shadowing is dynamically generated through QCD evolution.

Predictions for unmeasured nuclei and deuteron modifications are made.

Abstract

A global analysis of nuclear medium modifications of parton distributions is presented using deeply inelastic scattering data of various nuclear targets. Two obtained data sets are provided for quark and gluon nuclear modification factors, referred as nIMParton16. One is from the global fit only to the experimental data of isospin-scalar nuclei (Set A), and the other is from the fit to all the measured nuclear data (Set B). The scale-dependence is described by DGLAP equations with nonlinear corrections in this work. The Fermi motion and off-shell effect, nucleon swelling, and parton-parton recombination are taken into account together for modeling the complicated $x$-dependence of nuclear modification. The nuclear gluon shadowing in this paper is dynamically generated by the QCD evolution of parton splitting and recombination processes with zero gluon density at the input scale. Sophisticated nuclear dependence of nuclear medium effects is studied with only two free parameters. With the obtained free parameters from the global analysis, the nuclear modifications of parton distribution functions of unmeasured nuclei can be predicted in our model. Nuclear modification of deuteron is also predicted and shown with recent measurement at JLab.