Extended Slow-Roll Conditions and Primordial Fluctuations: Multiple Scalar Fields and Generalized Gravity

TL;DR

This paper extends slow-roll conditions to multiple scalar fields with non-minimal coupling and generalized gravity, providing formulas for spectral indices of perturbations.

Contribution

It introduces generalized slow-roll conditions for complex gravity theories and multiple fields, along with explicit formulas for spectral indices.

Findings

Derived slow-roll conditions for multiple non-minimally coupled scalar fields.

Provided simple formulas for spectral indices of scalar and tensor perturbations.

Extended the framework to $f(\,phi,R)$ gravity theories.

Abstract

As an extension of our previous study, we derive slow-roll conditions for multiple scalar fields which are non-minimally coupled with gravity and for generalized gravity theories of the form $f(\phi,R)$. We provide simple formulae of the spectral indices of scalar/tensor perturbations in terms of the slow-roll parameters.