Event-by-event fluctuations of mean transverse momentum in Pb-Pb and Xe-Xe collisions with ALICE

TL;DR

This study investigates event-by-event fluctuations of mean transverse momentum in Pb-Pb and Xe-Xe collisions at the LHC, revealing correlated particle emission and deviations from simple collision models.

Contribution

It provides new measurements of transverse momentum fluctuations in different collision systems and energies, highlighting the role of collective effects and model deviations.

Findings

Dynamical fluctuations indicate correlated particle emission.

Fluctuations decrease in central collisions.

Deviations from superposition of independent nucleon-nucleon collisions.

Abstract

Event-by-event fluctuations of the mean transverse momentum of charged particles produced in Pb-Pb and Xe-Xe collisions at $\sqrt{s_{\rm{NN}}}$ = 5.02 TeV and $\sqrt{s_{\rm{NN}}}$ = 5.44 TeV, respectively, are studied as a function of the charged-particle multiplicity using the ALICE detector at the LHC. Dynamical fluctuations are observed in both collision systems which indicate correlated particle emission. The central Pb-Pb and Xe-Xe collisions show a significant reduction of the fluctuation in comparison to peripheral collisions and are in qualitative agreement with previous measurements in Pb-Pb collisions at $\sqrt{s_{\rm{NN}}}$ = 2.76 TeV. The results are compared with the HIJING model. A clear deviation from simple superposition of independent nucleon-nucleon collisions scenario, where the final state particles are produced from superposition of particle emitting sources, is observed.