Measurements of net-charge fluctuations across various colliding systems with ALICE

Abstract

Event-by-event fluctuations of conserved quantities such as electric charge, baryon number, and strangeness in ultrarelativistic heavy-ion collisions provide insight into the properties of the quark– gluon plasma and the QCD phase diagram. The net-charge fluctuations in finite phase space are usually studied using the νdyn[+,−] observable, which is robust against the detection efficiency losses. This observable becomes equivalent to the strongly intensive quantity Σ with the proper scaling. In this analysis, the values of νdyn[+,−] are obtained with ALICE detector in various colliding systems, namely, pp at √ s=5.02 TeV, p–Pb at sNN=5.02 TeV, and Pb–Pb at √ sNN=2.76 and 5.02 TeV, and Xe–Xe at sNN=5.44 TeV. The observed dependence of νdyn[+,−] on chargedparticle density shows a regular smooth evolution of net-charge fluctuation from smaller to larger collision systems. Furthermore, the observed negative values of νdyn[+,−] indicate the dominance of correlation between the oppositely charged particle pairs as compared to that arising from the like-sign charge pairs. These findings are compared to predictions from HIJING, EPOS-LHC, and PYTHIA8 models. The effect of the kinematical acceptance has also been investigated by examining the νdyn[+,−] dependence on transverse momentum range as well as the width of the pseudorapidity window. The effect of the hadronic resonance decays is also looked into by comparing the experimental findings with the predictions of HIJING model.