Bubble of nothing decays of unstable theories

TL;DR

This paper demonstrates that in certain stabilized extra-dimensional theories, bubbles of nothing can form in de Sitter vacua, leading to spacetime decay, with decay rates remaining finite even as vacuum energy approaches zero.

Contribution

It shows that stabilized theories with positive vacuum energy can still decay via bubbles of nothing, extending previous understanding of instability mechanisms.

Findings

Bubbles of nothing exist in stabilized de Sitter vacua.

Decay rates do not vanish as vacuum energy approaches zero.

Potential lower bounds on compactification sizes are suggested.

Abstract

Theories with compact extra dimensions are sometimes unstable to decay into a bubble of nothing -- an instability resulting in the destruction of spacetime. We investigate the existence of these bubbles in theories where the moduli fields that set the size of the extra dimensions are stabilized at a positive vacuum energy -- a necessary ingredient of any theory that aspires to describe the real world. Using bottom-up methods, and focusing on a five-dimensional toy model, we show that four-dimensional de Sitter vacua admit bubbles of nothing for a wide class of stabilizing potentials. We show that, unlike ordinary Coleman-De Luccia tunneling, the corresponding decay rate remains non-zero in the limit of vanishing vacuum energy. Potential implications include a lower bound on the size of compactified dimensions.