Solar system tests of f(R) gravity

TL;DR

This paper analyzes how f(R) gravity theories perform in solar system tests, using both analytical and numerical methods, and discusses mechanisms like the chameleon effect to reconcile theory with observations.

Contribution

It provides a simplified derivation of solar system constraints on f(R) gravity and explores the role of the chameleon mechanism in satisfying observational tests.

Findings

The metric in f(R) gravity differs from observations when the Sun is in vacuum.

The chameleon mechanism can mitigate discrepancies between f(R) models and solar system data.

Analytic and numerical methods determine the viability of f(R) models against solar system tests.

Abstract

In this paper, we revisit the solar system tests of f(R) gravity. When the Sun sits in a vacuum, the field f' is light, which leads to a metric different from the observations. We reobtain this result in a simpler way by directly focusing on the equations of motion for f(R) gravity in the Jordan frame. The discrepancy between the metric in the f(R) gravity and the observations can be alleviated by the chameleon mechanism. The implications from the chameleon mechanism on the functional form f(R) are discussed. Considering the analogy of the solar system tests to the false vacuum decay problem, the effective potentials in different cases are also explored. The combination of analytic and numerical approaches enables us to ascertain whether an f(R) model can pass the solar system tests or not.