Solar System constraints to nonminimally coupled gravity

TL;DR

This paper extends Solar System tests to nonminimally coupled gravity theories, deriving constraints on their functions to ensure compatibility with observations and applying it to models explaining cosmic acceleration.

Contribution

It introduces a method to constrain nonminimally coupled gravity functions using Solar System tests, generalizing previous $f(R)$ gravity analyses.

Findings

Constraints on $f^1(R)$ and $f^2(R)$ functions derived from Solar System data

Application of constraints to models explaining cosmic acceleration

Demonstration of the method's effectiveness in testing NMC gravity theories

Abstract

We extend the analysis of Chiba, Smith and Erickcek \cite{CSE} of Solar System constraints on $f(R)$ gravity to a class of nonminimally coupled (NMC) theories of gravity. These generalize $f(R)$ theories by replacing the action functional of General Relativity (GR) with a more general form involving two functions $f^1(R)$ and $f^2(R)$ of the Ricci scalar curvature $R$. While the function $f^1(R)$ is a nonlinear term in the action, analogous to $f(R)$ gravity, the function $f^2(R)$ yields a NMC between the matter Lagrangian density $\LL_m$ and the scalar curvature. The developed method allows for obtaining constraints on the admissible classes of functions $f^1(R)$ and $f^2(R)$, by requiring that predictions of NMC gravity are compatible with Solar System tests of gravity. We apply this method to a NMC model which accounts for the observed accelerated expansion of the Universe.