Fluctuations and Correlations of Conserved Charges near the QCD Critical Point

TL;DR

This paper investigates how fluctuations and correlations of conserved charges like baryon number, electric charge, and strangeness behave near the QCD critical point at finite temperature and chemical potential, using an effective model.

Contribution

It provides detailed calculations of higher-order fluctuations and correlations, revealing their distinctive behavior near the chiral phase transition, aiding the search for the QCD critical point.

Findings

Second-order fluctuations show peaks or valleys at the phase transition.

Third-order fluctuations change signs during the transition.

Higher-order fluctuations are more effective for locating the critical point.

Abstract

We study the fluctuations and correlations of conserved charges, i.e. the baryon number, electric charge and the strangeness at finite temperature and nonzero baryon chemical potential with an effective model. The fluctuations are calculated up to the fourth-order and the correlations to the third-order. We find that the second-order fluctuations and correlations have a peak or valley structure when the chiral phase transition takes place with the increase of the baryon chemical potential; the third-order fluctuations and correlations change their signs during the chiral phase transition and the fourth-order fluctuations have two maximum and one minimum. we also depict contour plots of various fluctuations and correlations of conserved charges in the plane of temperature and baryon chemical potential. We find that higher order fluctuations and correlations of conserved charges are superior to the second-order ones to be used to search for the critical point in heavy ion collision experiments.