Evolution of cosmological perturbations in a brane-universe.

In our present Letter, we analyze the impact of the existence of extra dimensions on cosmology, in particular, on the evolution of cosmological perturbations. For a five-dimensional anti-de Sitter spacetime where ordinary matter is confined to a brane-universe, the equations governing the cosmological perturbations are presented in a form very close to the equations of standard cosmology. Two types of corrections appear: corrections due to the unconventional evolution of the homogeneous solution, which change the background-dependent coefficients of the equations, and corrections due to the curvature along the fifth dimension, which act as source terms in the evolution equations.