Dynamical compactification from de Sitter space

TL;DR

This paper demonstrates that de Sitter space can dynamically evolve into lower-dimensional geometries through nucleation, offering a new mechanism for compactification with implications for cosmology and the cosmological constant problem.

Contribution

It introduces a novel dynamical mechanism for compactification from de Sitter space via nucleation of non-singular geometries, expanding the landscape of solutions in Einstein gravity with flux.

Findings

Lower-dimensional vacua are populated differently than in eternal inflation.

Nucleation rates are higher for smaller cosmological constants within the same dimensionality.

The model proposes a slow-roll inflation triggered by the compactification process.

Abstract

We show that D-dimensional de Sitter space is unstable to the nucleation of non-singular geometries containing spacetime regions with different numbers of macroscopic dimensions, leading to a dynamical mechanism of compactification. These and other solutions to Einstein gravity with flux and a cosmological constant are constructed by performing a dimensional reduction under the assumption of q-dimensional spherical symmetry in the full D-dimensional geometry. In addition to the familiar black holes, black branes, and compactification solutions we identify a number of new geometries, some of which are completely non-singular. The dynamical compactification mechanism populates lower-dimensional vacua very differently from false vacuum eternal inflation, which occurs entirely within the context of four-dimensions. We outline the phenomenology of the nucleation rates, finding that the dimensionality of the vacuum plays a key role and that among vacua of the same dimensionality, the rate is highest for smaller values of the cosmological constant. We consider the cosmological constant problem and propose a novel model of slow-roll inflation that is triggered by the compactification process.