The QCD Critical End Point Under Strong Magnetic Fields

TL;DR

This paper investigates how strong magnetic fields influence the QCD phase diagram using the three-flavor Nambu--Jona-Lasinio model, revealing an expansion of the first order transition line and shifts in the critical end point's location.

Contribution

It provides new insights into the effects of magnetic fields on the QCD phase diagram, including the size of the transition line and the position of the critical end point, using a three-flavor NJL model.

Findings

The first order transition line expands with increasing magnetic field strength.

The critical end point's temperature increases under strong magnetic fields.

The chemical potential at the critical end point oscillates around the zero-field value.

Abstract

We use the three-flavor Nambu--Jona-Lasinio model, which includes strangeness and quark physical masses in the mean field approximation, to investigate the influence of strong magnetic fields on the QCD phase diagram covering the whole $T-\mu$ plane. It is found that the size of the first order transition line increases as the field strength increases so that a larger coexistence region for hadronic and quark matter should be expected for strong magnetic fields. The location of the critical end point is also affected by the presence of magnetic fields which invariably increase the temperature value at which the first order line terminates. On the other hand, the critical end point chemical potential value displays a subtle oscillation around the B=0 value for magnetic fields within the $10^{17}-10^{20} \, {\rm G}$ range. These findings may have non trivial consequences for the physics of magnetars and heavy ion collisions.