Confronting hydrodynamic predictions with Xe-Xe data

TL;DR

This paper tests hydrodynamic predictions for Xe-Xe collisions at the LHC against experimental data, confirming the scaling behavior and suggesting a non-spherical shape of the xenon nucleus.

Contribution

It provides the first confrontation of hydrodynamic predictions with Xe-Xe collision data, validating the model's robustness and revealing nuclear shape insights.

Findings

Predictions largely confirmed by experimental data

Scaling behavior observed across different collision systems

Evidence suggests non-spherical shape of $^{129}$Xe nucleus

Abstract

Comparing collision systems of different size, at near the same collision energy, offers us the opportunity to probe the scaling behavior and therefore the nature of the system itself. Recently, we made predictions for Xe-Xe collisions at 5.44 TeV using viscous hydrodynamic simulations, noting that the scaling from the larger Pb-Pb system is rather generic, and arguing that robust predictions can be made that do not depend on details of the model. Here we confront our predictions with measurements that were subsequently made in a short Xe-Xe run at the LHC by the ALICE, ATLAS, and CMS collaborations. We find that the predictions are largely confirmed. Of particular interest is a strong indication of a non-spherical shape for the $^{129}$Xe nucleus.