Nuclear shadowing and prompt photons at relativistic hadron colliders

TL;DR

This paper investigates how nuclear effects influence prompt photon production at high energies, aiming to use these measurements to better understand nuclear gluon distributions in proton-nucleus and nucleus-nucleus collisions at RHIC and LHC.

Contribution

It provides a detailed analysis of nuclear shadowing effects on prompt photon production and proposes using transverse momentum-dependent ratios to constrain nuclear gluon distributions.

Findings

Nuclear shadowing significantly affects prompt photon yields.

Transverse momentum ratios can reveal shadowing and antishadowing effects.

Results are relevant for interpreting data at RHIC and LHC.

Abstract

The production of prompt photons at high energies provides a direct probe of the dynamics of the strong interactions. In particular, one expect that it could be used to constrain the behavior of the nuclear gluon distribution in $pA$ and $AA$ collisions. In this letter we investigate the influence of nuclear effects in the production of prompt photons and estimate the transverse momentum dependence of the nuclear ratios $R_{pA} = {\frac{d\sigma (pA)}{dy d^2 p_T}} / A {\frac{d\sigma (pp)}{dy d^2 p_T}}$ and $R_{AA} = {\frac{d\sigma (AA)}{dy d^2 p_T}} / A^2 {\frac{d\sigma (pp)}{dy d^2 p_T}}$ at RHIC and LHC energies. We demonstrate that the study of these observables can be useful to determine the magnitude of the shadowing and antishadowing effects in the nuclear gluon distribution.