Instanton transition in thermal and moduli deformed de Sitter cosmology

TL;DR

This paper studies phase transitions in de Sitter cosmology deformed by thermal radiation and moduli fields, revealing instanton-mediated tunneling and smooth evolution scenarios.

Contribution

It introduces a framework for analyzing instanton transitions and phase behaviors in deformed de Sitter cosmology with thermal and moduli effects.

Findings

First and second order phase transitions identified.

Instanton solutions enable tunneling between cosmological states.

Pure de Sitter limit corresponds to creation from nothing.

Abstract

We consider the de Sitter cosmology deformed by the presence of a thermal bath of radiation and/or time-dependent moduli fields. Depending on the parameters, either a first or second order phase transition can occur. In the first case, an instanton allows a double analytic continuation. It induces a probability to enter the inflationary evolution by tunnel effect from another cosmological solution. The latter starts with a big bang and, in the case the transition does not occur, ends with a big crunch. A temperature duality exchanges the two cosmological branches. In the limit where the pure de Sitter universe is recovered, the tunnel effect reduces to a "creation from nothing", due to the vanishing of the big bang branch. However, the latter may be viable in some range of the deformation parameter. In the second case, there is a smooth evolution from a big bang to the inflationary phase.