Baseline for the cumulants of net-proton distributions at STAR

TL;DR

This paper compares STAR's measured cumulants of net-proton distributions in heavy-ion collisions with Poisson and Binomial baselines, revealing deviations at certain energies and comparing with model predictions.

Contribution

It provides a systematic analysis of net-proton cumulants against baseline models and compares experimental data with UrQMD and AMPT simulations.

Findings

Deviations from baseline measures at 19.6 and 27 GeV

Comparison with UrQMD and AMPT models

Conversion of net-proton to net-baryon fluctuations in AMPT

Abstract

We present a systematic comparison between the recently measured cumulants of the net-proton distributions by STAR for 0-5% central Au+Au collisions at $\sqrt{s_{NN}}$=7.7-200 GeV and two kinds of possible baseline measures, the Poisson and Binomial baselines. These baseline measures are assuming that the proton and anti-proton distributions independently follow Poisson statistics or Binomial statistics. The higher order cumulant net-proton data are observed to deviate from all the baseline measures studied at 19.6 and 27 GeV. We also compare the net-proton with net-baryon fluctuations in UrQMD and AMPT model, and convert the net-proton fluctuations to net-baryon fluctuations in AMPT model by using a set of formula.