Perturbations of brans worlds - art. no. 083513

We consider cosmological models where the universe, governed by Einstein's equations, is a piece of a five dimensional double-sided anti-de Sitter spa cetime (that is, a "Z(2)-symmetric bulk") with matter confined to its four dimensional Robertson-Walker boundary or "brane." We study the perturbation s of such models. We use conformally Minkowskian coordinates to disentangle the contributions of the bulk gravitons and of the motion of the brane. We find the restrictions put on the bulk gravitons when matter on the brane i s taken to be a scalar field and we solve in this case the brane perturbati on equations.