Net baryon number fluctuations across the chiral phase transition at finite density in the strong coupling lattice QCD

TL;DR

This study explores net-baryon number fluctuations near the chiral phase transition at finite density using strong coupling lattice QCD, revealing oscillatory behavior and negative cumulant ratios influenced by mesonic fluctuations.

Contribution

It introduces an auxiliary field Monte-Carlo method to account for mesonic fluctuations in lattice QCD and analyzes higher-order cumulant ratios across the phase transition.

Findings

Higher-order cumulant ratios oscillate around the phase boundary.

Negative regions of cumulant ratios shrink with increasing lattice size.

Results align with scaling analysis expectations.

Abstract

We investigate the net-baryon number fluctuations across the chiral phase transition at finite density in the strong coupling and chiral limit. Mesonic field fluctuations are taken into account by using the auxiliary field Monte-Carlo method. We find that the higher-order cumulant ratios, $S\sigma$ and $\kappa\sigma^2$, show oscillatory behavior around the phase boundary at $\mu/T\gtrsim 0.2$, and there exists the region where the higher-order cumulant ratios are negative. The negative region of $\kappa\sigma^2$ is found to shrink with increasing lattice size. This behavior agrees with the expectations from the scaling analysis.