# Electroweak monopoles and the electroweak phase transition

## TL;DR

This paper explores electroweak monopoles within the Standard Model extended by a Born-Infeld hypercharge field, analyzing their properties, cosmological production, and potential role in matter-antimatter asymmetry.

## Contribution

It introduces regular electroweak monopole solutions in a Born-Infeld extended Standard Model and studies their cosmological implications and impact on the electroweak phase transition.

## Key findings

- Monopoles are regular and their masses depend on the Born-Infeld parameter.
- Electroweak monopoles can delay the phase transition and make it more strongly first order.
- Mass bounds for monopoles are established based on cosmological constraints.

## Abstract

We consider an isolated electroweak monopole solution within the Standard Model with a non-linear Born-Infeld extension of the hypercharge gauge field. Monopole (and dyon) solutions in such an extension are regular and their masses are predicted to be proportional to the Born-Infeld mass parameter. We argue that cosmological production of electroweak monopoles may delay the electroweak phase transition and make it more strongly first order for monopole masses $M\gtrsim 9.3\cdot 10^3$ TeV, while the nucleosynthesis constraints on the abundance of relic monopoles impose the bound $M\lesssim 2.3\cdot 10^4$ TeV. The monopoles with a mass in this shallow range may be responsible for the dynamical generation of the matter-antimatter asymmetry during the electroweak phase transition.