Monopole-Bubble in Early Universe

TL;DR

This paper explores novel bubble decay channels in the early universe involving monopole-like structures, revealing a new solution with potential significance at high temperatures in scalar field cosmology.

Contribution

It introduces a new monopole-bubble solution in a high-temperature scalar field model coupled to gravity, expanding understanding of vacuum decay processes.

Findings

A new monopole-like bubble solution exists at high temperature.

The monopole-bubble has a higher Euclidean action than ordinary bubbles.

Production rate of monopole-bubbles can be significant under certain conditions.

Abstract

The nucleation and evolution of bubbles are investigated in the model of an $O(3)$-symmetric scalar field coupled to gravity in the high temperature limit. It is shown that, in addition to the well-known bubble of which the inside region is true vacuum, there exists another decay channel at high temperature which is described by a new solution such that a false vacuum region like a global monopole remains at the center of a bubble. The value of the Euclidean action of this bubble is higher than that of the ordinary bubble; however, the production rate of it can be considerable for a certain range of scalar potentials.