# Quantum chromodynamics axion in a hot and magnetized medium

## TL;DR

This paper investigates how a hot, magnetized medium influences the properties of the QCD axion, including its mass and topological susceptibility, using the Nambu--Jona-Lasinio model and accounting for magnetic catalysis effects.

## Contribution

It introduces a detailed analysis of axion properties in a hot, magnetized environment within the NJL model, incorporating magnetic catalysis and inverse magnetic catalysis effects.

## Key findings

- Axion mass and susceptibility are significantly affected by magnetic fields.
- Magnetic catalysis enhances the axion mass at low temperatures.
- Inverse magnetic catalysis influences the temperature dependence of axion properties.

## Abstract

It is analyzed the effects of a hot and magnetized medium on the axion mass, self-coupling and topological susceptibility when in presence of an anisotropic external magnetic field along the $z$-direction, within the Nambu--Jona-Lasinio effective model for quantum chromodynamics. The effects of both Magnetic Catalysis and Inverse Magnetic Catalysis are explicitly taken into account through appropriate matching of parameters with those from lattice Monte-Carlo numerical simulations. It is also analyzed the dependence of the results with respect to different model parametrizations in the context of the Nambu--Jona-Lasinio model.