Nuclear Parton Distributions - a DGLAP Analysis

TL;DR

This paper analyzes nuclear parton distributions using DGLAP evolution, fitting experimental data to provide a reliable parametrization of parton ratios in nuclei over a wide range of x and Q^2.

Contribution

It offers a comprehensive DGLAP-based analysis of nuclear parton distributions with a new numerical parametrization for practical use.

Findings

Q^2 evolution of F2 ratios agrees with NMC data

Parton ratio ratios are moderately sensitive to free distribution sets

Provides a numerical parametrization for all parton flavors in nuclei

Abstract

Nuclear parton distributions $f_A(x,Q^2)$ are studied within a framework of the DGLAP evolution. Measurements of $F_2^A/F_2^D$ in deep inelastic $lA$ collisions, and Drell--Yan dilepton cross sections measured in $pA$ collisions are used as constraints. Also conservation of momentum and baryon number is required. It is shown that the calculated $Q^2$ evolution of $F_2^{\rm Sn}/F_2^{\rm C}$ agrees very well with the recent NMC data, and that the ratios $R_f^A=f_A/f$ are only moderately sensitive to the choice of a specific modern set of free parton distributions. For general use, we offer a numerical parametrization of $R_f^A(x,Q^2)$ for all parton flavours $f$ in $A>2$, and at $10^{-6}\le x \le 1$ and $2.25 {\rm GeV}^2\le Q^2\le 10^4 {\rm GeV}^2$.