Abstract. We investigate the evolution of gravitational wave perturbations about a brane cosmology embedded in a five-dimensional anti-de Sitter bulk. During slow-roll inflation in a Randall–Sundrum brane-world, the zero mode of the five-dimensional graviton is generated, while the massive modes remain in their vacuum state. When the zero mode re-enters the Hubble radius during radiation domination, massive modes are generated. We show that modes decouple in the low-energy/near-brane limit and develop perturbative techniques to calculate the mode-mixing at finite energy.

Key words: cosmological perturbation theory; cosmology with extra dimensions; gravity waves

Received 18 August 2003, accepted for publication 27 August 2003
Published 30 October 2003