Scalar-Tensor Gravity Theory For Dynamical Light Velocity

Abstract

A gravity theory is developed with the metric ${\hat{g}}_{\mu \nu }=g_{\mu \nu }+B{\partial }_{\mu }\varphi {\partial }_{\nu }\varphi$. In the present universe the additional contribution from the scalar field in the metric ${\hat{g}}_{\mu \nu }$ can generate an acceleration in the expansion of the universe, without negative pressure and with a zero cosmological constant. In this theory, gravitational waves will propagate at a different speed from non-gravitational waves. It is suggested that gravitational wave experiments could test this observational signature.

Comments: 14 pages latex file. Additional material added. Accepted for publication in Physics Letters B