Higher Moments of Net-Baryon Distribution as Probes of QCD Critical Point

TL;DR

This study investigates higher moments of net-baryon distributions in heavy-ion collisions to identify observables less affected by experimental acceptance and late-stage effects, aiming to probe the QCD critical point.

Contribution

It demonstrates that Kurtosis and Skewness are robust observables for early collision stages and highlights differences in net-proton and net-baryon kurtosis at lower energies.

Findings

Kurtosis and Skewness are less sensitive to acceptance effects.

Kurtosis times σ² of net-proton differs from net-baryon at energies below 20 GeV.

Monte Carlo results deviate from theoretical predictions at low energies.

Abstract

It is crucially important to find an observable which is independent on the acceptance and late collision process, in order to search for the possible Critical Point predicted by QCD. By utilizing A Multi-Phase Transport (AMPT) model and Ultra Relativistic Quantum Molecular Dynamics (UrQMD) model, we study the centrality and evolution time dependence of higher moments of net-baryon distribution in Au + Au collisions at $\sqrt{s_{NN}}=17.3$ GeV. The results suggest that Kurtosis and Skewness are less sensitive to the acceptance effect and late collision process. Thus, they should be good observables providing the information of the early stage of heavy ion collision. In addition, our study shows that the Kurtosis times $\sigma^{2}$ of net-proton distribution are quite different to that of net-baryon when collisions energy is lower than $\sqrt{s_{NN}}$ = 20 GeV, the Monte Calor calculations on Kurtosis$\cdot\sigma^{2}$ have a deviation from the theoretical predictions.