The QCD phase diagram in the presence of an external magnetic field: the role of the inverse magnetic catalysis

TL;DR

This paper investigates how an external magnetic field influences the QCD phase diagram, particularly the critical end point, using a modified NJL model that accounts for inverse magnetic catalysis, revealing significant shifts in phase transition behavior.

Contribution

It introduces a magnetic field-dependent coupling in the NJL model to study inverse magnetic catalysis effects on the QCD phase diagram and CEP location.

Findings

CEP moves to lower chemical potentials with magnetic field.

Inverse magnetic catalysis causes the CEP to disappear.

Chiral transition remains first order under these conditions.

Abstract

The effect of an external magnetic field in QCD phase diagram, namely, in the the location of the critical end point (CEP) is investigated. Using the 2+1 flavor Nambu--Jona-Lasinio model with Polyakov loop, it is shown that when an external magnetic field is applied its effect on the CEP depends on the strength of the coupling. If the coupling depends on the magnetic field, allowing for inverse magnetic catalysis, the CEP moves to lower chemical potentials eventually disappearing, and the chiral restoration phase transition is always of first order.