Monte Carlo Glauber model with meson cloud: predictions for 5.44 TeV Xe+Xe collisions

TL;DR

This study uses a Monte Carlo Glauber model, including meson cloud effects, to predict centrality-dependent particle multiplicities and anisotropy coefficients in Xe+Xe and Pb+Pb collisions at LHC energies, providing insights into nuclear shape effects.

Contribution

It introduces a Monte Carlo Glauber model with meson cloud considerations to improve predictions of collision observables at high energies.

Findings

Meson cloud effects on multiplicity are small.

Eccentricity ratios indicate shape effects in Xe nuclei.

Triangularity is larger in Xe+Xe than in Pb+Pb at certain centralities.

Abstract

We study, within the Monte-Carlo Glauber model, centrality dependence of the midrapidity charged multiplicity density $dN_{ch}/d\eta$ and of the anisotropy coefficients $\varepsilon_{2,3}$ in Pb+Pb collisions at $\sqrt{s}=5.02$ TeV and in Xe+Xe collisions at $\sqrt{s}=5.44$ TeV. Calculations are performed for versions with and without nucleon meson cloud. The fraction of the binary collisions, $\alpha$, has been fitted to the data on $dN_{ch}/d\eta$ in Pb+Pb collisions. We obtain $\alpha\approx 0.09(0.13)$ with (without) meson cloud. The effect of meson cloud on the $dN_{ch}/d\eta$ is relatively small. For Xe+Xe collisions for $0$-$5$\% centrality bin we obtain $dN_{ch}/d\eta\approx 1149$ and $1134$ with and without meson cloud, respectively. We obtain $\varepsilon_2(\mbox{Xe})/\varepsilon_2(\mbox{Pb})\sim 1.45$ for most central collisions, and $\varepsilon_2(\mbox{Xe})/\varepsilon_2(\mbox{Pb})$ close to unity at $c\gtrsim 20$\%. We find a noticeable increase of the eccentricity in Xe+Xe collisions at small centralities due to the prolate shape of the Xe nucleus. The triangularity in Xe+Xe collisions is bigger than in Pb+Pb collisions at $c\lesssim 70$\%. We obtain $\varepsilon_3(\mbox{Xe})/\varepsilon_3(\mbox{Pb})\sim 1.3$ at $c\lesssim 1$\%.