Topological susceptibility and axion properties in the presence of a strong magnetic field within the three-flavor NJL model

TL;DR

This paper investigates how strong magnetic fields influence topological susceptibility and axion characteristics using a three-flavor NJL model, incorporating CP violation, and compares findings with lattice QCD and other models.

Contribution

It introduces a magnetic field-dependent coupling in the NJL model to study inverse magnetic catalysis effects on topological and axion properties at finite temperature and density.

Findings

Magnetic fields up to 1 GeV^2 significantly affect topological susceptibility.

The model reproduces inverse magnetic catalysis phenomena.

Results align with lattice QCD and chiral perturbation theory predictions.

Abstract

We analyze the topological susceptibility and the axion properties in the presence of an external uniform magnetic field, considering a three flavor NJL model that includes strong CP violation through a 't Hooft-like flavor mixing term. Both thermal and finite density effects are studied for magnetic fields up to 1 GeV$^2$, and the corresponding phase transitions are analyzed. To capture the inverse magnetic catalysis effect at finite temperatures and densities, a magnetic field-dependent coupling constant is considered. Our analytical and numerical results are compared with those previously obtained from lattice QCD, chiral perturbation theory and other effective models.