Chiral symmetry breaking in a uniform external magnetic field II. Symmetry restoration at high temperatures and chemical potentials

TL;DR

This paper investigates how external magnetic fields influence chiral symmetry breaking and restoration in quantum electrodynamics, revealing different phase transition orders at high temperatures and chemical potentials.

Contribution

It demonstrates that chiral symmetry is restored at high chemical potential via a first order transition, while at high temperature it undergoes a second order transition, extending previous work.

Findings

Chiral symmetry is restored above a critical chemical potential.

The phase transition at high temperature is second order.

The phase transition at high chemical potential is first order.

Abstract

Chiral symmetry is dynamically broken in quenched, ladder QED at weak gauge couplings when an external magnetic field is present. In this paper, we show that chiral symmetry is restored above a critical chemical potential and the corresponding phase transition is of first order. In contrast, the chiral symmetry restoration at high temperatures (and at zero chemical potential) is a second order phase transition.