Electromagnetic field with induced massive term: Case with scalar field

TL;DR

This paper investigates a cosmological model with interacting massless scalar and electromagnetic fields, where the electromagnetic field acquires an effective mass, leading to field decay and universe isotropization.

Contribution

It introduces a model with broken gauge invariance causing electromagnetic field mass induction within a Bianchi type-I universe.

Findings

Electromagnetic field vanishes as time approaches infinity.

Interaction induces isotropization of the universe.

Electromagnetic field equation includes an effective mass term.

Abstract

We consider an interacting system of massless scalar and electromagnetic field, with the Lagrangian explicitly depending on the electromagnetic potentials, i.e., interaction with broken gauge invariance. The Lagrangian for interaction is chosen in such a way that the electromagnetic field equation acquires an additional term, which in some cases is proportional to the vector potential of the electromagnetic field. This equation can be interpreted as the equation of motion of photon with induced nonzero rest-mass. This system of interacting fields is considered within the scope of Bianchi type-I (BI) cosmological model. It is shown that, as a result of interaction the electromagnetic field vanishes at $t \to \infty$ and the isotropization process of the expansion takes place.