Global Analysis of Nuclear Parton Distributions

TL;DR

This paper provides a comprehensive global analysis of nuclear parton distribution functions using diverse experimental data, employing next-to-leading order QCD calculations to improve understanding of nuclear effects in high-energy collisions.

Contribution

It introduces a new global QCD analysis incorporating multiple data sets and uncertainties, advancing the modeling of nuclear parton distributions with a consistent and comprehensive approach.

Findings

Universal nuclear modification factors fit all data sets well.

Uncertainties are estimated using the Hessian method.

The analysis supports the universality of nuclear effects across different processes.

Abstract

We present a new global QCD analysis of nuclear parton distribution functions and their uncertainties. In addition to the most commonly analyzed data sets for the deep-inelastic scattering of charged leptons off nuclei and Drell-Yan di-lepton production, we include also measurements for neutrino-nucleus scattering and inclusive pion production in deuteron-gold collisions. The analysis is performed at next-to-leading order accuracy in perturbative QCD in a general mass variable flavor number scheme, adopting a current set of free nucleon parton distribution functions, defined accordingly, as reference. The emerging picture is one of consistency, where universal nuclear modification factors for each parton flavor reproduce the main features of all data without any significant tension among the different sets. We use the Hessian method to estimate the uncertainties of the obtained nuclear modification factors and examine critically their range of validity in view of the sparse kinematic coverage of the present data. We briefly present several applications of our nuclear parton densities in hard nuclear reactions at BNL-RHIC, CERN-LHC, and a future electron-ion collider.