New bounds on vacuum decay in de Sitter space

TL;DR

This paper establishes new, more stringent bounds on the rate of vacuum decay in de Sitter space, enhancing understanding of early and current Universe cosmological models through a novel analytical approach.

Contribution

It introduces a novel method to derive tighter bounds on vacuum decay rates, extendable to non-minimally coupled and quadratic gravity theories.

Findings

Derived more restrictive bounds on vacuum decay in de Sitter space.

Extended the analysis to theories beyond Einstein-Hilbert gravity.

Provided additional restrictions specific to quadratic gravity.

Abstract

Vacuum decay in de Sitter space is a process of great physical interest, as it allows to rule out cosmological models in the early and current Universe. Its rate may be described in terms of an instanton in Euclidean space called bounce and it is usually interpreted as thermally assisted quantum tunneling. According to analytical and numerical evidence in the literature, a bounce exists only for certain values of the Hubble parameter in single scalar field theories with Einstein-Hilbert gravity. In the present paper, we rely on a novel approach to provide more stringent bounds, which may be easily extended to theories with non-minimally coupled and quadratic gravity. An additional restriction is also derived, which specifically applies to the latter.