Centrality and energy dependence of charged particles in p+A and A+A collisions from running coupling $k_{T}$-factorization

TL;DR

This paper analyzes how particle production in high-energy proton-nucleus and nucleus-nucleus collisions depends on energy and collision centrality, using an advanced gluon distribution model within the $k_T$-factorization framework.

Contribution

It extends previous numerical analyses by incorporating two additional unintegrated gluon distributions, improving the understanding of particle multiplicities in A+A collisions.

Findings

Good agreement with A+A collision data.

Need for better proton gluon distribution modeling in p+A collisions.

Highlights importance of impact parameter dependence.

Abstract

We extend the numerical analysis of the energy and centrality dependence of particle multiplicities at midrapidity in high-energy p+A and A+A collisions from a running coupling $k_T$-factorization formula made in~\cite{Dumitru:2018gjm} by considering two unintegrated gluon distributions that were left out. While a good agreement with the experimental data in A+A collisions is achieved, improving the description of those observables in p+A collisions calls for a better understanding of the proton unintegrated gluon distribution at larger values of $x$ and also the use of a realistic impact parameter dependence.