Primordial Gravitational Waves in Bimetric Gravity

Understand

We study primordial tensor power-spectra generated during inflation in bimetric gravity.

• More precisely, we examine a homogeneous expanding spacetime in a minimal bimetric model with an inflaton and calculate tensor perturbations on the homogeneous background under slow-roll approximation.
• In terms of the mass eigenstates, only the power-spectrum of the massless state remains constant and both the power-spectrum of the massive state and the cross power-spectrum rapidly decay during inflation.
• The amplitude of the physical power-spectrum is suppressed due to the flavor mixing.