Baseline study for higher moments of net-charge distribution at RHIC energies

Abstract

Lattice QCD models predict the presence of a critical point in the QCD phase diagram where the first order phase transition between the hadron gas and Quark-Gluon Plasma ceases to exist. Higher moments of conserved quantities, such as net-charge, net-baryon number and net-strangeness, are proposed to be sensitive probes for locating the critical point. The moments of net-charge distributions have been studied as a function of centrality for {Au+Au} collisions at $\sqrt{s_{\rm NN}}$ = 7.7 to 200 GeV using three event generators, {\it viz.}, UrQMD, HIJING, and THERMINATOR-2. The effect of centrality selection, resonance production, as well as contributions from particle species to the net-charge moments and their products have been studied. It is observed that mean of the net-charge distributions are dominated by net-protons, whereas standard deviation, skewness and kurtosis closely follow net-pion distributions. These results, along with the predictions from Hadron Resonance Gas (HRG) model, are presented.