Viable Mimetic Completion of Unified Inflation-Dark Energy Evolution in Modified Gravity

TL;DR

This paper shows that mimetic $F(R)$ gravity can unify early inflation and late dark energy acceleration, successfully matching observational data and providing a natural exit from inflation.

Contribution

It demonstrates the viability of mimetic $F(R)$ gravity to describe both inflation and dark energy, overcoming limitations of traditional $F(R)$ models.

Findings

Inflationary era can be realized in mimetic $F(R)$ gravity.

Model predictions are compatible with Planck and BICEP2/Keck data.

Graceful exit from inflation is achieved via growing curvature perturbations.

Abstract

In this paper, we demonstrate that a unified description of early and late-time acceleration is possible in the context of mimetic $F(R)$ gravity. We study the inflationary era in detail and demonstrate that it can be realized even in mimetic $F(R)$ gravity where traditional $F(R)$ gravity fails to describe the inflation. By using standard methods we calculated the spectral index of primordial curvature perturbations and the scalar-to-tensor ratio. We use two $F(R)$ gravity models and as it turns out, for both the models under study the observational indices are compatible with both the latest Planck and the BICEP2/Keck array data. Finally, the graceful exit from inflation is guaranteed by the existence of growing curvature perturbations when the slow-roll era ends.