Fluctuation Spectrum from a Scalar-Tensor Bimetric Gravity Theory

Predictions of the CMB spectrum from a bimetric gravity theory (BGT) [1] are presented. The initial inflationary period in BGT is driven by a vanishingly small speed of gravitational waves vg in the very early universe. This initial inflationary period is insensitive to the choice of scalar field potential and initial values of the scalar field. After this initial period of inflation, vg will increase rapidly and the effects of a potential will become important. We show that a quadratic potential introduced into BGT yields an approximately flat spectrum with inflation parameters: ns = 0.98, nt = −0.027, αs = −3.2× 10 and αt = −5.0× 10, with r ≥ 0.014.