Energy dependence of moments of the net-charge multiplicity distributions in Au+Au collisions at RHIC

Abstract

The Beam Energy Scan program at the Relativistic Heavy Ion Collider (RHIC) is aimed to probe the QCD phase diagram in the vicinity of a possible critical point. Higher moments of multiplicity distributions of conserved quantities are predicted to be sensitive to the fluctuations due to critical point. Lattice QCD predictions and statistical thermal models suggest that the susceptibility of the medium formed in heavy-ion collisions can be related to various moments (Mean (µ) = x, Variance (s2) = (x - µ)2, Skewness (S) = (x - µ)3/s3 and Kurtosis (?)= (x - µ)4/s4 - 3, of the conserved quantities like net-baryon number (?B), net-electric charge (?Q) and net-strangeness (?S). Non monotonic deviation in the higher moments from the baseline predictions would indicate the existence of the QCD critical point. We present various moments and their products for the net-charge multiplicity distributions in Au+Au collisions at different energies ranging from sNN = 7.7 to 200 GeV, measured by PHENIX experiment at RHIC. The experimental results are compared with different heavy-ion collision models, which do not include the QCD phase transition and critical point.