Nonlinear corrections for the nuclear gluon distribution in $eA$ processes

TL;DR

This paper analytically investigates the nonlinear corrections to nuclear gluon distributions at small x and Q^2, highlighting their significance especially at NLO and for larger nuclei, using the GLR-MQ evolution framework.

Contribution

It provides a detailed analysis of nonlinear QCD corrections to nuclear gluon distributions at small x, comparing NLO and NNLO effects with the GLR-MQ evolution and existing models.

Findings

Nonlinear corrections are more significant at NLO than NNLO.

Gluon distributions increase with decreasing x and larger atomic number A.

Results align with the Rausch-Guzey-Klasen evolution within uncertainties.

Abstract

An analytical study with respect to the nonlinear corrections for the nuclear gluon distribution function in the next-to-leading order approximation at small $x$ is presented. We consider the nonlinear corrections to the nuclear gluon distribution functions at low values of $x$ and $Q^{2}$ using the parametrization $F_{2}(x,Q^{2})$ and using the nuclear modification factors where they have been obtained with the Khanpour-Soleymaninia-Atashbar-Spiesberger-Guzey model. The CT18 gluon distribution is used as baseline proton gluon density at $Q_{0}^{2}=1.69~\mathrm{GeV}^2$. We discuss the behavior of the gluon densities in the next-to-leading order and the next-to-next-to-leading order approximations at the initial scale $Q_{0}^{2}$, as well as the modifications due to the nonlinear corrections. We find the QCD nonlinear corrections are significant for the next-to-leading order accuracy than the next-to-next-to-leading order for light and heavy nuclei. The results of the nonlinear GLR-MQ evolution equation are similar to those obtained with the Rausch-Guzey-Klasen gluon upward and downward evolutions within the uncertainties. The magnitude of the gluon distribution with the nonlinear corrections increases with a decrease of $x$ and an increase of the atomic number A.