Magnetized QCD phase diagram

TL;DR

This paper explores how external magnetic fields influence the QCD phase diagram using an extended NJL model, revealing that magnetic fields can shift the critical end point and potentially change the nature of the phase transition.

Contribution

It introduces a magnetic field dependent coupling in the NJL model to account for inverse magnetic catalysis and studies its effects on the QCD phase diagram.

Findings

Inverse magnetic catalysis shifts the critical end point.

High magnetic fields may turn the chiral transition at zero chemical potential first-order.

Magnetic fields influence the phase transition structure in QCD.

Abstract

Using the 2+1 flavor Nambu--Jona-Lasinio (NJL) model with the Polyakov loop, we determine the structure of the QCD phase diagram in an external magnetic field. Beyond the usual NJL model with constant couplings, we also consider a variant with a magnetic field dependent scalar coupling, which reproduces the Inverse Magnetic Catalysis (IMC) at zero chemical potential. We conclude that the IMC affects the location of the Critical End Point, and found indications that, for high enough magnetic fields, the chiral phase transition at zero chemical potential might change from an analytic to a first-order phase transition.