Cosmological implications of 5-dimensional Brans-Dicke theory

The five-dimensional Brans-Dicke theory naturally provides two scalar fields by the Killing reduction mechanism. These two scalar fields could account for the accelerated expansion of the universe. We test this model and constrain its parameter by using the type Ia supernova (SN Ia) data. We find that the best fit value of the 5-dimensional Brans-Dicke coupling constant is ω=−1.9. This result is also consistent with other observations such as the baryon acoustic oscillation (BAO).