Influence of the inverse magnetic catalysis and the vector interaction in the location of the critical end point

TL;DR

This paper investigates how inverse magnetic catalysis and vector interactions influence the position of the critical end point in the QCD phase diagram using a Polyakov--Nambu--Jona-Lasinio model, revealing competing effects that depend on magnetic field strength.

Contribution

It introduces an analysis of the combined effects of inverse magnetic catalysis and vector interactions on the CEP location within the (2+1) Polyakov--Nambu--Jona-Lasinio model, highlighting their opposing influences.

Findings

Inverse magnetic catalysis shifts the CEP to lower chemical potentials.

Magnetic fields above 0.3 GeV^2 hinder CEP temperature increase.

For fields below 0.1 GeV^2, CEP moves to more experimentally accessible regions.

Abstract

The effect of a strong magnetic field on the location of the critical end point (CEP) in the QCD phase diagram is discussed under different scenarios. In particular, we consider the contribution of the vector interaction and take into account the inverse magnetic catalysis obtained in lattice QCD calculations at zero chemical potential. The discussion is realized within the (2+1) Polyakov--Nambu--Jona-Lasinio model. It is shown that the vector interaction and the magnetic field have opposite competing effects, and that the winning effect depends strongly on the intensity of the magnetic field. The inverse magnetic catalysis at zero chemical potential has two distinct effects for magnetic fields above $\gtrsim 0.3$ GeV$^2$: it shifts the CEP to lower chemical potentials, hinders the increase of the CEP temperature and prevents a too large increase of the baryonic density at the CEP. For fields $eB<0.1$ GeV$^2$ the competing effects between the vector contribution and the magnetic field can move the CEP to regions of temperature and density in the phase diagram that could be more easily accessible to experiments.