Cosmology and brane worlds: a review

Cosmological consequences of the brane world scenario are reviewed in a pedagogical manner. According to the brane world idea, the standard model particles are confined on a hypersurface (a so-called brane), which is embedded in a higher-dimensional spacetime (the so-called bulk). We begin our review with the simplest consistent brane world model: a single brane embedded in a five-dimensional anti-de Sitter spacetime. Then we include a scalar field in the bulk and discuss in detail the difference with the anti-de Sitter case. The geometry of the bulk spacetime is also analysed in some depth. Finally, we investigate the cosmology of a system with two branes and a bulk scalar field. We comment on brane collisions and summarize some open problems of brane world cosmology.