Classical evolution and quantum generation in generalized gravity theories including string corrections and tachyon: Unified analyses

TL;DR

This paper develops a unified cosmological perturbation framework for generalized gravity theories, including string corrections and tachyon fields, applicable to scalar and tensor perturbations during inflation.

Contribution

It provides a comprehensive, unified analysis of classical evolution and quantum generation in diverse gravity theories with string and tachyon effects, extending previous models.

Findings

Unified formulas for scalar and tensor perturbations.

Application to generalized slow-roll inflation scenarios.

Derivation of power spectra in various inflation models.

Abstract

We present cosmological perturbation theory based on generalized gravity theories including string theory correction terms and a tachyonic complication. The classical evolution as well as the quantum generation processes in these variety of gravity theories are presented in unified forms. These apply both to the scalar- and tensor-type perturbations. Analyses are made based on the curvature variable in two different gauge conditions often used in the literature in Einstein's gravity; these are the curvature variables in the comoving (or uniform-field) gauge and the zero-shear gauge. Applications to generalized slow-roll inflations and its consequent power spectra are derived in unified forms which include wide range of inflationary scenarios based on Einstein's gravity and others.