Charged-particle multiplicity fluctuations in Pb–Pb collisions at √sNN = 2.76 TeV

Abstract

Abstract Measurements of event-by-event fluctuations of charged-particle multiplicities in Pb–Pb collisions at √sNN = 2.76 TeV using the ALICE detector at the CERN Large Hadron Collider (LHC) are presented in the pseudo- rapidity range |η| < 0.8 and transverse momentum 0.2 < pT < 2.0 GeV/c. The amplitude of the fluctuations is expressed in terms of the variance normalized by the mean of the multiplicity distribution. The η and pT dependences of the fluctuations and their evolution with respect to collision centrality are investigated. The multiplicity fluctuations tend to decrease from peripheral to central collisions. The results are compared to those obtained from HIJING and AMPT Monte Carlo event generators as well as to experimental data at lower collision energies. Additionally, the measured multi- plicity fluctuations are discussed in the context of the isother- mal compressibility of the high-density strongly-interacting system formed in central Pb–Pb collisions.