Generalised cosmology of codimension-two braneworlds

TL;DR

This paper explores the cosmological behavior of codimension-two braneworlds, demonstrating that while they can reproduce standard cosmology, they do not inherently solve the cosmological constant problem.

Contribution

The authors construct a thick brane model and analyze its cosmology, highlighting the lack of a self-tuning mechanism in non-supersymmetric Einstein gravity.

Findings

Model reduces to standard FRW cosmology

No evidence of self-tuning for the cosmological constant

Challenges remain in generalizing brane content beyond pure tension

Abstract

It has recently been argued that codimension-two braneworlds offer a promising line of attack on the cosmological constant problem, since in such models the Hubble rate is not directly related to the brane tension. We point out challenges to building more general models where the brane content is not restricted to pure tension. In order to address these challenges, we construct a thick brane model which we linearize around a well known static solution. We show that the model's cosmology does reduce to standard FRW behaviour, but find no hint of a self-tuning mechanism which might help solve the cosmological constant problem whithin the context of non-supersymmetric Einstein gravity.