Mapping the critical region along the second-order chiral phase boundary

TL;DR

This study uses the functional renormalization group method on the quark-meson model to analyze the size of the critical scaling region near the second-order chiral phase transition at finite chemical potential, revealing its systematic shrinkage with increasing chemical potential.

Contribution

It provides a detailed analysis of the critical scaling region in the quark-meson model at finite chemical potential using fRG, highlighting how the region diminishes as chemical potential increases.

Findings

Scaling region shrinks with higher chemical potential

LPA' yields slightly smaller scaling region than LPA

Critical exponents are extracted from the data

Abstract

We investigate the extent of the critical scaling region of the chiral phase transition at finite chemical potential within the quark-meson (QM) model using the functional renormalization group (fRG) approach. By analyzing the scaling behavior of the chiral order parameter and correlation length with respect to temperature and pion mass near the second-order phase transition, we extract critical exponents from the data and quantify the range over which the scaling relations remain valid. We find that both the leading order and the next-to-leading-order scaling regions systematically shrink as the chemical potential increases. This behavior is observed in both the local potential approximation (LPA) and its extension including anomalous dimensions (LPA'), with qualitatively consistent results, while the scaling region in LPA' is slightly smaller than that in LPA.