Thermo-magnetic nonlocal NJL model in the real and imaginary time formalisms

TL;DR

This paper investigates the effects of a magnetic field on a nonlocal NJL model at finite temperature using real and imaginary time formalisms, revealing magnetic catalysis of deconfinement and increased thermodynamic instability.

Contribution

It introduces a mixed approach to temperature incorporation in a nonlocal NJL model with magnetic field effects, including confinement via quasiparticle poles and analyzing phase transitions.

Findings

Magnetic catalysis occurs for both chiral and deconfinement transitions.

Magnetic field enhances thermodynamic instability.

No splitting of critical temperatures in weak magnetic fields.

Abstract

In this article we study a nonlocal Nambu--Jona-Lasinio (nNJL) model with a Gaussian regulator in presence of a uniform magnetic field. We take a mixed approach to the incorporation of temperature in the model, and consider aspects of both real and imaginary time formalisms. We include confinement in the model through the quasiparticle interpretation of the poles of the propagator. The effect of the magnetic field in the deconfinement phase transition is then studied. It is found that, like with chiral symmetry restoration, magnetic catalysis occurs for the deconfinement phase transition. It is also found that the magnetic field enhances the thermodynamical instability of the system. We work in the weak field limit, i.e. $(eB)<5m_\pi^2$. At this level there is no splitting of the critical temperatures for chiral and deconfinement phase transitions.