Cosmological perturbations in a generalized gravity including tachyonic condensation

Abstract

We present unified ways of handling the cosmological perturbations in a class of gravity theory covered by a general action. This gravity includes our previous generalized $f(\ensuremath{\varphi},R)$ gravity and the gravity theory motivated by the tachyonic condensation. We present a general prescription to derive the power spectra generated from vacuum quantum fluctuations in the slow-roll inflation era. An application is made to a slow-roll inflation based on the tachyonic condensation with an exponential potential.