Inflation in $f(R,\phi)$-theories and mimetic gravity scenario

TL;DR

This paper explores inflationary models within $f(R,)$-theories coupled with a scalar field, analyzing their dynamics, observational predictions, and extensions to include dark matter via mimetic gravity.

Contribution

It introduces a class of $f(R,)$-models supporting inflation with realistic exit dynamics and extends the framework to incorporate dark matter through mimetic gravity.

Findings

Models support early-time acceleration with effective cosmological constant.

Predictions for spectral index and tensor-to-scalar ratio align with cosmological data.

Framework allows for extensions to include dark matter.

Abstract

We investigate inflation within $f(R,\phi)$-theories, where a dynamical scalar field is coupled to gravity. A class of models which can support early-time acceleration with the emerging of an effective cosmological constant at high curvature is studied. The dynamics of the field allow for exit from inflation leading to the correct amount of inflation in agreement with cosmological data. Furthermore, the spectral index and tensor-to-scalar ratio of the models are carefully analyzed. A generalization of the theory to incorporate dark matter in the context of mimetic gravity, and further extensions of the latter, are also discussed.