Probing QCD chiral cross over transition in heavy ion collisions with fluctuations

TL;DR

This paper proposes that measuring higher moments of net proton fluctuations in heavy ion collisions can experimentally probe the QCD chiral crossover transition, supported by theoretical modeling and comparison with STAR data.

Contribution

It introduces a method to detect the QCD chiral crossover via fluctuation measurements and provides theoretical predictions using the Polyakov loop extended quark-meson model with non-perturbative dynamics.

Findings

Clear signal of the chiral crossover in net baryon number fluctuations

Theoretical predictions align with STAR experimental data

Fluctuation patterns depend on energy and centrality in collisions

Abstract

We argue that by measuring higher moments of the net proton number fluctuations in heavy ion collisions (HIC) one can probe the QCD chiral cross over transition experimentally. We discuss the properties of fluctuations of the net baryon number in the vicinity of the chiral crossover transition within the Polyakov loop extended quark-meson model at finite temperature and baryon density. The calculation includes non-perturbative dynamics implemented within the functional renormalization group approach. We find a clear signal for the chiral crossover transition in the fluctuations of the net baryon number. We address our theoretical findings to experimental data of STAR Collaboration on energy and centrality dependence of the net proton number fluctuations and their probability distributions in HIC.