Induced gravity on intersecting brane-worlds Part II: Cosmology

TL;DR

This work extends the brane-world cosmology program to a six-dimensional setup with two intersecting codimension-one branes whose intersection hosts a codimension-two four-dimensional universe with induced gravity. By deriving the cosmological equations for a moving brane and the intersection, the authors obtain a Friedmann equation at the intersection that includes standard DGP-like terms from the codimension-one branes and novel six-dimensional bulk contributions, controlled by the brane angle. A key result is that these six-dimensional terms can source late-time acceleration even in the absence of conventional energy content, generalizing self-acceleration from codimension-one to higher codimensions and highlighting energy exchange between branes and the bulk. The work provides a mirage cosmology framework for higher-codimension systems, but also notes potential issues such as energy non-conservation at the intersection and possible ghosts, pointing to future work on low-energy effective actions and numerical analyses. Overall, the paper demonstrates a pathway to geometrical acceleration in higher-codimension brane worlds and lays groundwork for further exploration of their phenomenology and stability.

Abstract

We explore cosmology of intersecting braneworlds with induced gravity on the branes. We find the cosmological equations that control the evolution of a moving codimension one brane and a codimension two brane that sits at the intersection. We study the Friedmann equation at the intersection, finding new contributions from the six dimensional bulk. These higher dimensional contributions allow us to find new examples of self-accelerating configurations for the codimension two brane at the intersection and we discuss their features.