The impact of non-minimally coupled gravity on vacuum stability

TL;DR

This paper investigates how non-minimal coupling to gravity affects vacuum decay rates, revealing that it can stabilize or destabilize vacua depending on the background spacetime, with significant implications for cosmology.

Contribution

It extends the thin-wall approximation to include non-minimal coupling and provides a comprehensive numerical analysis of its effects on vacuum stability.

Findings

In de Sitter space, large non-minimal coupling stabilizes the vacuum.

In Minkowski space, small non-minimal coupling can increase decay rates.

Non-minimal coupling significantly alters vacuum decay probabilities depending on the background.

Abstract

We consider vacuum decay in the presence of a non-minimal coupling to gravity. We extend the usual thin-wall solution to include the non-minimal coupling. We also perform a full numerical study and discuss the validity of the new thin-wall approximation. Implications of a large cosmological constant, whose influence on the geometry boosts the tunnelling rate, are discussed. Our results show that the influence of the non-minimal coupling differs significantly between the cases of Minkowski and deSitter backgrounds. In the latter the decay probability quickly decreases when the coupling grows and in fact the vacuum can be made absolutely stable simply due to introduction of the non-minimal coupling. In the case of Minkowski background the effect is much weaker and the decay rate even increases for small values of the non-minimal coupling.