Viability of f(R) Theories with Additional Powers of Curvature

TL;DR

This paper examines a modified gravity model with additional curvature powers, analyzing its viability for explaining cosmic acceleration while satisfying local constraints, and finds that consistent parameter ranges are hard to identify.

Contribution

It provides a detailed analysis of the parameter space for a specific f(R) gravity model with multiple curvature terms, assessing its cosmological and local constraints.

Findings

Parameter ranges for the model are highly restricted.

The theory struggles to satisfy all observational constraints simultaneously.

No unique viable parameter set was identified.

Abstract

We consider a modified gravity theory, f(R)=R-a/R^n+bR^m, in the metric formulation, which has been suggested to produce late time acceleration in the Universe, whilst satisfying local fifth-force constraints. We investigate the parameter range for this theory, considering the regimes of early and late-time acceleration, Big Bang Nucleosynthesis and fifth-force constraints. We conclude that it is difficult to find a unique range of parameters for consistency of this theory.