Quintessential inflation in Palatini $f(R)$ gravity

TL;DR

This paper explores a class of inflationary models within Palatini $f(R)$ gravity, demonstrating successful inflation and quintessence with specific scalar potentials, and providing testable predictions for primordial tensors.

Contribution

It introduces a new inflationary and quintessence model in Palatini $f(R)$ gravity with specific potentials, showing compatibility with observations and making future testable predictions.

Findings

Inflation and quintessence achieved with quadratic and inverse quartic potentials.

Palatini modifications have subdominant effects during kination.

Predictions for primordial tensors are within reach of upcoming experiments.

Abstract

We investigate in detail a family of quintessential inflation models in the context of $R+R^2$ Palatini modified gravity. We find that successful inflation and quintessence are obtained with an inflaton scalar potential that is approximately quadratic in inflation and inverse quartic in quintessence. We show that corrections for the kination period due to Palatini modified gravity are subdominant, while the setup does not challenge constraints on modified gravity from solar system observations and microscopic experiments, in contrast to the metric case. We obtain concrete predictions regarding primordial tensors, to be probed in the near future.