Charge-dependent two-particle correlations for unidentifi?ed charged particles in Xe-Xe collisions at sNN = 5.44 TeV

Abstract

Heavy-ion collisions at high energies in the Large Hadron Collider (LHC) create a quark-gluon plasma. The rapid expansion of this medium causes its constituents to experience collective motion. This leaves signatures in the final-state observables, e.g. the transverse momentum distribution and two-particle correlations. In particular, the balance function probes the radial flow by quantifying the two-particle correlation of oppositely-charged particles created at the same point in space and time. The balance function of particles of low transverse momentum shows a dependence on the event multiplicity for heavy-ion collisions, i.e. between gold nuclei (Au-Au) or lead nuclei (Pb-Pb). Recently, this trend was also observed at low transverse momenta in small collision systems such as proton-proton (p-p) or proton-lead (p-Pb) collisions. The origin of the collective effects in these collision systems is still unclear. To bridge the gap in system size, this thesis presents the balance function of unidentified charged particles in collisions between two xenon nuclei (Xe-Xe) with sNN =5.44 TeV. The results are compatible with smaller collision systems, i.e. p-p and p-Pb, as well as Pb-Pb collisions. This implies that the collective effects are of similar origin in all systems. However, additional studies are needed, in particular on the balance functions for identified charged particles in Xe-Xe.