Chiral Symmetry Restoration and Deconfinement in the Contact Interaction Model of Quarks with a Parallel Electric and Magnetic Fields

TL;DR

This paper investigates how parallel electric and magnetic fields influence chiral symmetry and confinement transitions in QCD using a contact interaction model, revealing effects like magnetic catalysis, electric chiral restoration, and inverse catalysis consistent with lattice results.

Contribution

It provides a unified analysis of electric and magnetic field effects on QCD phase transitions within a contact interaction framework, including finite temperature behavior and phase diagram sketch.

Findings

Magnetic catalysis at zero temperature in magnetic fields.

Electric fields tend to restore chiral symmetry and deconfinement.

Inverse electric and magnetic catalysis observed at finite temperature.

Abstract

We study the impact of steady, homogeneous, and external parallel electric and magnetic field strength ($eE\parallel eB$), on the chiral symmetry breaking-restoration and confinement-deconfinement phase transitions. We also sketch the phase diagram of quantum chromodynamics (QCD) at finite temperature $T$ and in the presence of background fields. Our unified formalism for this study is based on the Schwinger-Dyson equations, symmetry preserving vector-vector contact interaction model of quarks, and the proper time regularization scheme. At $T=0$, in the purely magnetic case ($eE\rightarrow 0$), we observe the well known magnetic catalysis effect. On the other hand, in the pure electric field background ($eB\rightarrow 0$), the electric field tends to restore the chiral symmetry and deconfinement above the pseudo-critical electric field $eE^{\chi, C}_c$. In the presence of both $eE$ and $eB$: we find the magnetic catalysis effect in the particular region where $eB$ dominates over $eE$, whereas, we observe the chiral inhibition (or electric chiral rotation) effect, when $eE$ stand over $eB$. At finite $T$, in the pure electric field case, the phenomenon of inverse electric catalysis appears to exist in our model. On the other hand for pure magnetic field background, we notice the magnetic catalysis effect in the mean-field approximation and inverse magnetic catalysis with $eB$-dependent coupling. The combined effect of both $eE$ and $eB$ on the pseudo-critical $T^{\chi, C}_c$ yields the inverse electromagnetic catalysis, with and without $eB-$dependent effective coupling of the model. Our findings are satisfactory in agreement with already predicted results by lattice simulations and other reliable effective models of QCD.