Brane worlds, string cosmology, and AdS/CFT - art. no. 084027

Using the thin-shell formalism we discuss the motion of domain walls in de Sitter and anti-de Sitter (AdS) time-dependent bulks. This motion results i n a dynamics for the brane scale factor. We show that in the case of a clea n brane the scale factor describes both singular and nonsingular universes, with phases of contraction and expansion. These phases can be understood a s quotients of AdS spacetime by a discrete symmetry group. We discuss this effect in some detail, and suggest how the AdS/CFT correspondence could be applied to obtain a nonperturbative description of brane-world string cosmo logy.