External magnetic fields and the chiral phase transition in QED at nonzero chemical potential

TL;DR

This paper investigates how a uniform external magnetic field influences the chiral phase transition in quenched ladder QED at nonzero chemical potential, revealing inverse magnetic catalysis at certain magnetic field strengths.

Contribution

It provides new insights into the effects of magnetic fields on chiral symmetry breaking in QED, highlighting the phenomenon of inverse magnetic catalysis at specific field ranges.

Findings

Inverse magnetic catalysis occurs at a local maximum of the effective potential.

Magnetic catalysis is observed at the true minimum of the effective potential.

The behavior depends on the strength of the external magnetic field.

Abstract

Inspired by recent discussions of inverse magnetic catalysis in the literature, we examine the effects of a uniform external magnetic field on the chiral phase transition in quenched ladder QED at nonzero chemical potential. In particular, we study the behaviour of the effective potential as the strength of the magnetic field is varied while the chemical potential is held constant. For a certain range of the magnetic field, the effective potential develops a local maximum. Inverse magnetic catalysis is observed at this maximum, whereas the usual magnetic catalysis is observed at the true minimum of the effective potential.