On the gluon shadowing effect in light and heavy nuclei at small $x$

TL;DR

This paper develops new TMD gluon densities for nuclei using a color dipole formalism and geometrical scaling, fitting experimental data to predict gluon shadowing effects at small x across different nuclei.

Contribution

It introduces a novel method combining the color dipole approach with geometrical scaling to derive nuclear gluon distributions from proton TMD gluon densities.

Findings

Derived nuclear gluon distributions consistent with experimental data.

Predicted gluon shadowing effects at small x for various nuclei.

Compared results with existing models and approaches.

Abstract

We propose new Transverse Momentum Dependent (TMD) gluon densities in nuclei. Our method is based on a combination of the color dipole scattering formalism, within which we interpret the nuclear deep inelastic structure functions $F_2^{A}(x, Q^2)$ and well established property of geometrical scaling from nucleons to nuclei. As an input, we employ the TMD gluon density in a proton which provides a self-consistent simultaneous description of the numerous HERA and LHC data on $pp$, $ep$ and $\gamma p$ processes. After fitting the relevant phenomenological parameters to the experimental data on the ratios $F_2^{A}(x, Q^2)/F_2^{A^\prime}(x, Q^2)$ for several nuclear targets $A$ and $A^\prime$, we derive the corresponding nuclear gluon distributions. Then, we make predictions for gluon shadowing effects at small Bjorken $x$ in their dependence of the mass number $A$. A comparison with other approaches is given.