ALICE results on system-size dependence of charged-particle multiplicity density in p–Pb, Pb–Pb and Xe–Xe collisions

Abstract

Particle production at LHC energies involves the interplay of hard (perturbative) and soft (non-perturbative) QCD processes. Global observables, such as the charged-particle multiplicity, are related to the initial geometry and the energy density produced in the collision. They are important to characterise relativistic heavy-ion collisions and to constrain model calculations. The LHC produced Xenon-Xenon collisions for the first time in October 2017. New results on the primary charged-particle pseudorapidity density, and its pseudorapidity and centrality dependence are presented for this lighter and deformed nucleus, and compared to measurements obtained for lead ions. New results will also be presented for p-Pb collisions at the highest energy of 8.16 TeV, as part of an overview of all the measurements at LHC Run 1 and 2 energies. These studies allow us to investigate the evolution of particle production with energy and system size and to compare models based on various particle production mechanisms and different initial conditions.

Mesonic Resonance Production in p–Pb, Pb–Pb and Xe–Xe Collisions with ALICE at the LHC

“…A similar trend in p T as a function of charged particle multiplicity is also observed for other resonances [4]. The charged particle multiplicity in the most central p-Pb collisions have similar order of magnitude as peripheral heavy ion collisions [8]. The new results of p T may lead to a better understanding of mass ordering (particles with similar masses have similar p T ) which is observed in central and semi-central Pb-Pb collisions as expected from the hydrodynamic expansion of the system [2].…”

Transverse Momentum and Pseudorapidity Dependence of Particle Production in Xe–Xe Collision at sNN=5.44 TeV

“…Since the nucleons of the Xe 129 nucleus is fewer than that of Pb 208 nucleus, the investigation of Xe-ion collisions can roughly bridge or connect the gap between and Pb ion collisions. As a good intermediate-size system, the Xe-Xe colliding system brings a wonderful opportunity to discuss the colliding-system size dependence of multiparticle production in high-energy nuclear collisions [8,9]. e nucleus collisions at high energies offer numerous experimental data about charged particle production, such as pions, kaons, and protons.…”