# Einstein-Maxwell-axion theory: Dyon solution with regular electric field

## TL;DR

This paper explores static, spherically symmetric solutions in Einstein-Maxwell-axion theory, revealing axionic dyons with regular electric fields, including those with vanishing central electric fields and Coulombian asymptotes.

## Contribution

It introduces and analyzes new solutions describing axionic dyons with regular electric fields, highlighting the effects of axion-photon coupling on electric charge structure.

## Key findings

- Solutions with regular electric fields at the center are found.
- Electric charge can be effectively induced by axion-photon interaction.
- Constraints on electric and scalar charges are discussed.

## Abstract

In the framework of Einstein-Maxwell-axion theory we consider static spherically symmetric solutions, which describe a magnetic monopole in the axionic environment. These solutions are interpreted as the solutions for an axionic dyon, the electric charge of which is composite, i.e., in addition to the standard central electric charge, it includes an effective electric charge induced by the axion-photon coupling. We focus on the analysis of that solutions, which are characterized by the electric field regular at the center. Special attention is paid to the solutions with the electric field, which is vanishing at the center, has the Coulombian asymptote and thus display an extremum at some distant sphere. Constraints on the electric and effective scalar charges of such an object are discussed.