QCD critical region and higher moments for three flavor models

TL;DR

This paper investigates the QCD critical region using effective (2+1)-flavor models, analyzing higher moments and susceptibilities to identify the critical endpoint and understand phase transition characteristics.

Contribution

It introduces a novel derivative technique to compute higher order quark-number susceptibilities and compares mean-field and renormalized approaches in QCD models.

Findings

Higher order moments are enhanced near the critical point.

Sign structure of susceptibilities varies across the phase diagram.

Back-reaction effects influence the critical behavior.

Abstract

One of the distinctive feature of the QCD phase diagram is the possible emergence of a critical endpoint. The critical region around the critical point and the path dependency of the critical exponents is investigated within effective chiral (2+1)-flavor models with and without Polyakov-loops. Results obtained in no-sea mean-field approximations where a divergent vacuum part in the fermion-loop contribution is neglected, are confronted to the renormalized ones. Furthermore, the modifications caused by the back-reaction of the matter fluctuations on the pure Yang-Mills system are discussed. Higher order, non-Gaussian moments of event-by-event distributions of various particle multiplicities are enhanced near the critical point and could serve as a probe to determine its location in the phase diagram. By means of a novel derivative technique higher order generalized quark-number susceptibilities are calculated and their sign structure in the phase diagram is analyzed.