Brane-world cosmology

A simple model of the brane-world cosmology has been proposed, which is cha racterized by four parameters, namely, the bulk cosmological constant, the spatial curvature of the universe, the radiation strength arising from bulk space-time and the breaking parameter of Z(2)-symmetry. The bulk space-tim e is assumed to be locally static five-dimensional analogue of the Schwarzs child-Anti-de Sitter space-time, and then the location of three-brane is de termined by the metric junction. The resulting Friedmann equation recovers the standard cosmology, and a new term arises if Z(2)-symmetry is not assum ed, which behaves as a cosmological term in the early universe, next turns to a negative curvature term, and finally damps rapidly.