Cosmological perturbations in a generalized gravity including tachyonic condensation

TL;DR

This paper develops a unified framework for analyzing cosmological perturbations in a broad class of gravity theories, including those with tachyonic condensation, and applies it to a specific inflation model.

Contribution

It introduces a general method to derive power spectra in various gravity theories, including tachyonic models, extending previous approaches.

Findings

Unified approach to cosmological perturbations in generalized gravity

Application to tachyonic condensation inflation model

Derivation of power spectra from quantum fluctuations

Abstract

We present unified ways of handling the cosmological perturbations in a class of gravity theory covered by a general action in eq. (1). This gravity includes our previous generalized $f(\phi,R)$ gravity and the gravity theory motivated by the tachyonic condensation. We present 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.