Evolution of cosmological perturbations in a brane-universe

TL;DR

This paper investigates how extra dimensions in a five-dimensional Anti-de Sitter spacetime influence the evolution of cosmological perturbations, highlighting modifications to standard cosmological equations due to brane-world effects.

Contribution

It presents a clear formulation of perturbation equations in brane-world cosmology, incorporating effects of extra dimensions and curvature along the fifth dimension.

Findings

Modified evolution equations for cosmological perturbations due to extra dimensions

Identification of background-dependent coefficient changes

Source terms arising from fifth-dimensional curvature

Abstract

The present article analyses the impact on cosmology, in particular on the evolution of cosmological perturbations, of the existence of extra-dimensions. The model considered here is that of a five-dimensional Anti-de Sitter spacetime where ordinary matter is confined to a brane-universe. The homogeneous cosmology is recalled. The equations governing the evolution of cosmological perturbations are presented in the most transparent way: they are rewritten in a form very close to the equations of standard cosmology with two types of corrections: a. corrections due to the unconventional evolution of the homogeneous solution, which change the background-dependent coefficients of the equations; b. corrections due to the curvature along the fifth dimension, which act as source terms in the evolution equations.