Brane World Cosmology, the CMB and the Radion

Abstract

Recent developments in the theory of extra dimensions have opened up avenues to confront such theories with cosmological tests. We discuss a brane-world model with a bulk scalar field, motivated by supergravity. The low-energy effective action is derived and physical constraints on the parameters of the model discussed. The cosmological evolution of the brane-world moduli is investigated and it is shown that one of the moduli is a quintessence field. The CMB predictions are computed. Finally, the possibility that the radion field in brane-worlds could be a chameleon field is investigated.

Comments: 11 pages, 6 figures, to appear in the proceedings of the DPU Workshop: The Density Fluctuations in the Universe: Beyond the Inflaton Paradigm (Athens, June 2004)