Modified f(R) gravity unifying R^m inflation with \LambdaCDM epoch

TL;DR

The paper presents a modified $f(R)$ gravity framework designed to unify early-time $R^m$ inflation with a late-time $\Lambda$CDM epoch, while remaining consistent with local gravity tests. By constructing $f(R)$ models that dominate as $\alpha R^m$ at high curvature and approach small residual values at late times, it achieves inflation and a small cosmological constant without violating solar-system constraints, with the scalar degree of freedom becoming heavy in dense environments. The analysis shows near-GR behavior for the current universe, predicts only tiny deviations from standard $\Lambda$CDM, and discusses possible future evolutions (quintessence-like or transient phantom) depending on further $\delta f(R)$ terms. Overall, the work highlights a theoretically viable route to unify inflation and dark energy within $f(R)$ gravity and outlines the observational and theoretical steps needed to distinguish it from GR.

Abstract

We consider modified $f(R)$ gravity which may unify $R^m$ early-time inflation with late-time $Λ$CDM epoch. It is shown that such model passes the local tests (Newton law, stability of Earth-like gravitational solution, very heavy mass for additional scalar degree of freedom) and suggests the realistic alternative for General Relativity. Various scenarios for future evolution of $f(R)$ $Λ$CDM era are discussed.