Induced gravity on intersecting brane-worlds Part I: Maximally symmetric solutions

TL;DR

This paper investigates intersecting brane-world models with induced gravity, discovering maximally symmetric solutions, self-accelerating and self-tuning solutions, and discussing implications for late-time cosmic acceleration and matter inclusion.

Contribution

It introduces new self-accelerating and self-tuning solutions in intersecting brane-world models with induced gravity, expanding understanding of modified gravity scenarios.

Findings

Found maximally symmetric solutions for branes and intersections.

Discovered self-accelerating solutions with see-saw gravity modifications.

Identified challenges in higher-dimensional models for realistic late-time acceleration.

Abstract

We explore models of intersecting brane-worlds with induced gravity terms on codimension one branes and on their intersection. Maximally symmetric solutions for the branes and the intersection are found. We find new self-accelerating solutions. In a 6d spacetime, the solutions realize the see-saw modification of gravity where the UV scale of the modification to 4d gravity is determined by 6d Planck scale given by $M_6 \sim 10^{-3}$eV and the IR scale of the modification is determined by $M_6^2/M_4 \sim H_0 \sim 10^{-42}$ GeV where $H_0$ is present-day Hubble scale. We find that it is increasingly difficult to construct phenomenologically viable models in higher-dimensional spacetime due to the necessity to have the lower value for the fundamental Planck scale to realize the late time acceleration. It is found that the system also admits self-tuning solutions where the tension at the intersection does not change the geometry of the intersection. The induced gravity terms can avoid the necessity to compactify the extra dimensions. Finally, we discuss the possibility to have ordinary matter at the intersection, without introducing any regularisation, using the induced gravity terms.