Slow-roll inflation in the Jordan frame

Abstract

Inflation models based on scalar-tensor theories of gravity are formulated in the Jordan frame, but are most often analyzed in the Einstein frame. The transformation between the frames is not always desirable. In this work, we formulate slow-roll conditions in the Jordan frame. This is achieved by comparing different background quantities and approximations on the same spatial slice in both frames. We use these approximations to derive simple equations that can be applied to compute inflation model observables in terms of Jordan frame quantities only. Finally, we apply some of the results to analyze generalized induced gravity models and compare them with the latest observations.

Topics & Concepts