Nature of chiral phase transition in QED$_3$ at zero density

TL;DR

This paper investigates the nature of the chiral phase transition in massless QED$_3$ at finite and zero temperature, revealing second-order transitions at finite temperature and higher-order transitions at zero temperature, based on susceptibility analysis.

Contribution

It introduces an analysis of chiral and thermal susceptibilities to determine the order of phase transitions in QED$_3$ near critical points.

Findings

Second-order phase transition at finite temperature with critical exponents less than 1.

Higher-order continuous phase transition at zero temperature.

Critical behavior depends on temperature and fermion flavor number.

Abstract

Based on the feature of chiral susceptibility and thermal susceptibility at finite temperature, the nature of chiral phase transition around the critical number of fermion flavors ($N_c$) and the critical temperature ($T_c$) at a fixed fermion flavors number in massless QED$_3$ are investigated. It is showed that, at finite temperature the system exhibits a second-order phase transition at $N_c$ or $T_c$ and each of the estimated critical exponents is less than 1, while it reveals a higher-order continuous phase transition around $N_c$ at zero temperature.