Inclusive heavy-flavour production at central and forward rapidity in Xe-Xe collisions at $\sqrt{s_{\rm NN}}=5.44$ TeV

TL;DR

This paper reports the first measurements of heavy-flavour decay muons and electrons in Xe-Xe collisions at 5.44 TeV, revealing suppression patterns that inform understanding of quark-gluon plasma properties and energy loss mechanisms.

Contribution

It provides the first experimental data on heavy-flavour decay leptons in Xe-Xe collisions at this energy, comparing suppression with Pb-Pb results to explore medium effects.

Findings

Observed suppression factor up to 2.5 in central collisions

Similar suppression levels in Xe-Xe and Pb-Pb systems at comparable multiplicities

Provides constraints for theoretical models of parton energy loss

Abstract

The first measurements of the production of muons and electrons from heavy-flavour hadron decays in Xe-Xe collisions at $\sqrt{s_{\rm NN}}$ = 5.44 TeV, using the ALICE detector at the LHC, are reported. The measurement of the nuclear modification factor $R_{\rm AA}$ is performed as a function of transverse momentum $p_{\rm T}$ in several centrality classes at forward rapidity ($2.5 < y <4$) and midrapidity ($\vert y \vert < 0.8$) for muons and electrons from heavy-flavour hadron decays, respectively. A suppression by a factor up to about 2.5 compared to the binary-scaled pp reference is observed in central collisions at both central and forward rapidities. The $R_{\rm AA}$ of muons from heavy-flavour hadron decays is compared to previous measurements in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV. When the nuclear modification factors are compared in the centrality classes 0-10% for Xe-Xe collisions and 10-20% for Pb-Pb collisions, which have similar charged-particle multiplicity density, a similar suppression, with $R_{\rm AA} \sim 0.4$ in the $p_{\rm T}$ interval $4 < p_{\rm T} < 8$ GeV/$c$, is observed. The comparison of the measured $R_{\rm AA}$ values in the two collision systems brings new insights on the properties of the quark-gluon plasma by investigating the system-size and path-length dependence of medium-induced parton energy loss. The results of muons and electrons from heavy-flavour hadron decays provide new constraints to model calculations.