Multiplicities in Au-Au and Cu-Cu collisions at \sqrt{s_{NN}} = 62.4 and 200 GeV

TL;DR

This study tests whether charged-particle multiplicities in Au-Au and Cu-Cu collisions at RHIC energies follow a negative binomial distribution, finding that the hypothesis is generally rejected, but not in all cases.

Contribution

It provides a detailed statistical analysis of multiplicity distributions in heavy-ion collisions, highlighting the conditions under which the negative binomial model is applicable.

Findings

Negative binomial distribution is generally rejected for most collision classes.

Systematic errors influence the acceptance of the hypothesis.

In Au-Au collisions at 62.4 GeV, the hypothesis cannot be rejected.

Abstract

Likelihood ratio tests are performed for the hypothesis that charged-particle multiplicities measured in Au-Au and Cu-Cu collisions at $\sqrt{s_{NN}} = 62.4$ and 200 GeV are distributed according to the negative binomial form. Results suggest that the hypothesis should be rejected in the all classes of collision systems and centralities of PHENIX-RHIC measurements. However, the application of the least-squares test statistic with systematic errors included shows that for the collision system Au-Au at $\sqrt{s_{NN}} = 62.4$ GeV the hypothesis could not be rejected in general.