# Solar System Constraints on Gauss-Bonnet Mediated Dark Energy

## TL;DR

This paper investigates how the Gauss-Bonnet term, when coupled to a scalar field, affects solar system gravity, deriving constraints from planetary and spacecraft data to limit its role in cosmic acceleration.

## Contribution

It provides the first detailed analysis of solar system constraints on Gauss-Bonnet mediated dark energy, including post-Newtonian corrections and observational bounds.

## Key findings

- Mass-dependent 1/r^7 correction to Newtonian potential
- Deviations from Einstein gravity in light-bending
- Extremely tight bounds on Gauss-Bonnet energy parameter

## Abstract

Although the Gauss-Bonnet term is a topological invariant for general relativity, it couples naturally to a quintessence scalar field, modifying gravity at solar system scales. We determine the solar system constraints due to this term by evaluating the post-Newtonian metric for a distributional source. We find a mass dependent, 1/r^7 correction to the Newtonian potential, and also deviations from the Einstein gravity prediction for light-bending. We constrain the parameters of the theory using planetary orbits, the Cassini spacecraft data, and a laboratory test of Newton's law, always finding extremely tight bounds on the energy associated to the Gauss-Bonnet term. We discuss the relevance of these constraints to late-time cosmological acceleration.