Fluctuations of Temperature in the Polyakov-loop extended Nambu--Jona-Lasinio Model

TL;DR

This paper studies temperature fluctuations in hot QCD matter using a PNJL model, revealing non-monotonic behaviors of high-order cumulant ratios near phase transitions, which could be observed in heavy-ion experiments.

Contribution

It provides a detailed analysis of temperature fluctuation behaviors across phase transitions in the PNJL model, highlighting non-monotonic cumulant ratio structures near the critical point.

Findings

High-order cumulant ratios exhibit non-monotonic variations across the chiral phase transition.

Distinct peak and dip structures in cumulant ratios are observed at low baryon chemical potential.

These structures weaken and vanish at high chemical potential, linked to phase transition sharpening.

Abstract

We investigate temperature fluctuations in hot QCD matter using a 3-flavor Polyakov-loop extended Nambu--Jona-Lasinio (PNJL) model. The high-order cumulant ratios $R_{n2}$ ($n>2$) exhibit non-monotonic variations across the chiral phase transition, characterized by slight fluctuations in the chiral crossover region and significant oscillations around the critical point. In contrast, distinct peak and dip structures are observed in the cumulant ratios at low baryon chemical potential. These structures gradually weaken and eventually vanish at high chemical potential as they compete with the sharpening of the chiral phase transition, particularly near the critical point and the first-order phase transition. Our results indicate that these non-monotonic peak and dip structures in high-order cumulant ratios are associated with the deconfinement phase transition. This study quantitatively analyzes temperature fluctuation behavior across different phase transition regions, and the findings are expected to be observed and validated in heavy-ion collision experiments through measurements of event-by-event mean transverse momentum fluctuations.