Inflation and Reheating in f(R,h) theory formulated in the Palatini formalism

TL;DR

This paper develops a new inflation model within f(R,h) modified gravity in the Palatini formalism, analyzing its compatibility with observational data and exploring reheating dynamics.

Contribution

It introduces a novel inflationary framework using non-minimal scalar-curvature coupling in Palatini f(R,h) gravity and derives observationally consistent parameters.

Findings

Existence of parameter space compatible with Planck 2018 data

Explicit inflation models for specific f(R,h) choices

Reheating temperature and e-folds calculated for various equations of state

Abstract

A new model for inflation using modified gravity in the Palatini formalism is constructed. Here non-minimal coupling of scalar field h with the curvature R as a general function f(R,h) is considered. Explicit inflation models for some choices of f(R,h) are developed. By writing an equivalent scalar-tensor action for this model and going over to Einstein frame, slow roll parameters are constructed. There exists a large parameter space which satisfies values of n_s and limits on r compatible with Planck 2018 data. Further, we calculate reheating temperature and the number of e-folds at the end of reheating for different values of equation of state parameter for all the constructed models.