Centrality and pseudorapidity dependence of the charged-particle multiplicity density in Xe–Xe collisions at √sNN=5.44 TeV

Abstract

In this Letter, the ALICE Collaboration presents the first measurements of the charged-particle multiplicity density, , and total charged-particle multiplicity, , in Xe–Xe collisions at a centre-of-mass energy per nucleon–nucleon pair of . The measurements are performed as a function of collision centrality over a wide pseudorapidity range of . The values of at mid-rapidity and for central collisions, normalised to the number of nucleons participating in the collision () as a function of follow the trends established in previous heavy-ion measurements. The same quantities are also found to increase as a function of , and up to the 5% most central collisions the trends are the same as the ones observed in Pb–Pb at a similar energy. For more central collisions, the Xe–Xe scaled multiplicities exceed those in Pb–Pb for a similar . The results are compared to phenomenological models and theoretical calculations based on different mechanisms for particle production in nuclear collisions. All considered models describe the data reasonably well within 15%.