Exact and slow-roll solutions for exponential power-law inflation connected with f(R) gravity and observational constraints

TL;DR

This paper explores exponential power-law inflation within f(R) gravity, reconstructs specific models from observational data, and demonstrates their consistency with Planck 2018 constraints on key cosmological parameters.

Contribution

It provides a method to reconstruct f(R) gravity models from exponential power-law inflation using Hamilton-Jacobi formalism and compares their predictions with observational data.

Findings

Both models fit Planck 2018 data well.

Reconstructed potentials include Starobinsky and Higgs.

Models yield correct spectral index and tensor-to-scalar ratio.

Abstract

We investigate an ability of the exponential power-law inflation to be phenomenologically correct model of the early universe. GR scalar cosmology equations we study in Ivanov-Salopek-Bond (or Hamilton-Jacobi like) representation where the Hubble parameter $H$ is the function of a scalar field $\phi$. Such approach admits calculation of the potential for given $H(\phi)$ and consequently reconstruction of $f(R)$ gravity in parametric form. By this manner the Starobinsky potential and non-minimal Higgs potential (and consequently the corresponding $f(R)$ gravity) were reconstructed using constraints on model's parameters. Also comparison to observation (PLANCK 2018) data shows that both models give correct values for scalar spectral index and tensor-to-scalar ratio under wide range of exponential-power-law model's parameters.