Study of the Fluctuations of Net-charge and Net-protons Using Higher Order Moments

TL;DR

This paper reports on measurements of higher order moments of net-charge and net-proton distributions in heavy-ion collisions, providing insights into the fluctuations and possible signals of the QCD critical point.

Contribution

It presents the first STAR results on high moments of these distributions at 200 GeV, showing scaling behavior and consistency with models lacking a QCD critical point.

Findings

High moments scale with the number of participating nucleons.

Ratios of fourth to second order cumulants are consistent with non-critical models.

Results do not indicate signals of the QCD critical point.

Abstract

We present the STAR preliminary results on mid-rapidity and low transverse momentum mean, standard deviation, skewness, and kurtosis of net-charge and net-proton distributions in Au+Au and Cu+Cu collisions at $\sqrt{s_{NN}}$ = 200 GeV for various collision centralities. All the measured high moments of these distributions can be scaled by the number of participating nucleons, consistent with the soft process emissions. The ratios of fourth to second order cumulants of both the net-charge and net-proton distributions are consistent with models without QCD critical point.