Vacuum decay and quadratic gravity: the massive case

TL;DR

This paper extends previous studies of false vacuum decay in quadratic gravity to include massive scalar fields, analyzing how mass influences decay dynamics and the viability of vacuum transitions in various gravitational theories.

Contribution

It generalizes earlier work by incorporating massive scalar fields into the analysis of vacuum decay within quadratic gravity, exploring effects on decay rates and theoretical viability.

Findings

Scalar fields reach asymptotic values faster with mass.

Massive fields allow a broader class of theories for vacuum decay.

Higher-order kinetic terms and dimensional changes are briefly considered.

Abstract

False vacuum decay in field theory may be formulated as a boundary value problem in Euclidean space. In a previous work, we studied its solution in single scalar field theories with quadratic gravity and used it to find obstructions to vacuum decay. For simplicity, we focused on massless scalar fields and false vacua with a flat geometry. In this paper, we generalize those findings to massive scalar fields with the same gravitational interactions, namely an Einstein-Hilbert term, a quadratic Ricci scalar, and a non-minimal coupling. We find that the scalar field reaches its asymptotic value faster than in the massless case, in principle allowing for a wider range of theories that may accommodate vacuum decay. Nonetheless, this hardly affects the viability of the bounce in the scenarios here considered. We also briefly consider other physically interesting theories by including higher-order kinetic terms and changing the number of spacetime dimensions.