Search for the QCD Critical Point: Higher Moments of Net-proton Multiplicity Distributions

TL;DR

This paper investigates higher moments of net-proton multiplicity distributions to search for the QCD critical point, comparing experimental data with theoretical models to identify potential non-monotonic signals indicative of critical phenomena.

Contribution

It introduces the use of higher moments of net-proton distributions as a method to locate the QCD critical point, providing baseline model comparisons and proposing non-monotonicity as a key signature.

Findings

Measured moment products are compared with model predictions.

Non-monotonic dependence of moments suggests possible critical point signals.

Baseline results from models help interpret experimental fluctuations.

Abstract

Higher moments of event-by-event net-proton multiplicity distributions have been applied to search for the QCD critical point. Model results are used to provide a baseline for this search. The measured moment products, $\kappa\sigma^2$ and $S\sigma$ of net-proton distributions, which are directly connected to the thermodynamical baryon number susceptibility ratio in Lattice QCD and Hadron Resonance Gas (HRG) model, are compared to the transport and thermal model results. We argue that a non-monotonic dependence of $\kappa \sigma^2$ and $S \sigma$ as a function of beam energy can be used to search for the QCD critical point.