Moments of net-charge multiplicity distribution in Au+Au collisions measured by the PHENIX experiment at RHIC

TL;DR

This paper presents measurements of higher moments of net-charge multiplicity distributions in Au+Au collisions at RHIC, aiming to detect signs of the QCD critical point through energy and centrality dependence analysis.

Contribution

It provides the first comprehensive analysis of higher moments of net-charge distributions across a wide energy range at RHIC, comparing results with models lacking a QCD critical point.

Findings

No non-monotonic behavior observed in higher moments.

Results consistent with models without a QCD critical point.

Energy dependence of moments aligns with baseline expectations.

Abstract

Beam Energy Scan (BES) program at RHIC is important to search for the existence of the critical point in the QCD phase diagram. Lattice QCD have shown that the predictions of the susceptibility of the medium formed in heavy-ion collisions can be sensitive to the various moments (mean ($\mu$) =${<x>}$, variance ($\sigma^2$) = ${<(x-\mu)^2>}$, skewness (S) = $\frac{<(x-\mu)^3>}{\sigma^3}$ and kurtosis ($\kappa$) =$\frac{<(x-\mu)^4>}{\sigma^4} -3$) of conserved quantities like net-baryon number ($\Delta$B), net-electric charge ($\Delta$Q) and net-strangeness ($\Delta$S). Any non-monotonic behavior of the higher moments would confirm the existence of the QCD critical point. The recent results of the higher moments of net-charge multiplicity distributions for Au+Au collisions at $\sqrt{s}_{NN}$ varying from 7.7 GeV to 200 GeV from the PHENIX experiment at RHIC are presented. The energy and centrality dependence of the higher moments and their products (S$\sigma$ and $\kappa\sigma^{2}$) are shown for the net-charge multiplicity distributions. Furthermore, the results are compared with the values obtained from the heavy-ion collision models, where there is no QCD phase transition and critical point.