Brane World Cosmological Perturbations

TL;DR

This paper analyzes gravitational perturbations in brane world models, providing general solutions and junction conditions, and discusses implications for inflation and stability of perturbations.

Contribution

It offers a comprehensive solution for bulk perturbations and establishes conditions linking gravitational waves to anisotropic stress in brane worlds.

Findings

Gravitational waves are linked to anisotropic stress in most cases.

Perturbations in brane worlds are stable unlike the radion.

Provides general solutions and junction conditions for brane perturbations.

Abstract

We consider a brane world and its gravitational linear perturbations. We present a general solution of the perturbations in the bulk and find the complete perturbed junction conditions for generic brane dynamics. We also prove that (spin 2) gravitational waves in the great majority of cases can only arise in connection with a non-vanishing anisotropic stress. This has far reaching consequences for inflation in the brane world. Moreover, contrary to the case of the radion, perturbations are stable.