# Magnetic field instability driven by anomalous magnetic moments of massive fermions and electroweak interaction with background matter

## TL;DR

This paper demonstrates that massive fermions with anomalous magnetic moments interacting electroweakly with background matter can induce electric currents that destabilize magnetic fields, potentially amplifying seed fields in astrophysical objects like neutron stars.

## Contribution

It provides an exact solution-based calculation of the electric current in external fields and shows how this current leads to magnetic field instability, a novel mechanism relevant to astrophysics.

## Key findings

- Electric current along magnetic field due to massive fermions with anomalous magnetic moments.
- Magnetic field instability caused by this current in Maxwell equations.
- Potential significant amplification of seed magnetic fields in neutron stars.

## Abstract

It is shown that the electric current of massive fermions along the external magnetic field can be excited in the case when particles possess anomalous magnetic moments and electroweakly interact with background matter. This current is calculated on the basis of the exact solution of the Dirac equation in the external fields. It is shown that the magnetic field becomes unstable if this current is taken into account in the Maxwell equations. Considering a particular case of a degenerate electron gas, which can be found in a neutron star, it is revealed that the seed magnetic field can be significantly enhanced. The application of the results to astrophysics is also discussed.