# A general study of chameleon fifth force in gravity space experiments

## TL;DR

This paper studies the behavior of chameleon scalar fields in gravity space experiments, analyzing their potential detectability through fifth force effects in satellite configurations like MICROSCOPE.

## Contribution

It provides a detailed calculation of the scalar field profile in realistic satellite geometries without relying on common approximations, clarifying detectability prospects.

## Key findings

- Scalar field profiles depend on satellite geometry and parameters.
- Fifth force effects can be significant or screened depending on conditions.
- Results challenge previous assumptions about detectability in space experiments.

## Abstract

This article investigates the profile of the scalar field of a scalar-tensor theory subject to the chameleon mechanism in the context of gravity space missions like the MICROSCOPE experiment. It analyses the experimental situations for models with an inverse power law potential that can in principle induce a fifth force inside the satellite, hence either be detected or constrained. As the mass of the scalar field depends on the local matter density, the screening of the scalar field depends crucially on both the parameters of the theory (potential and non-minimal coupling to matter) and on the geometry of the satellite. We calculate the profile of the scalar field in 1-, 2- and 3-dimensional satellite configurations without relying on the thick or thin shell approximations for the scalar field. In particular we consider the typical geometry with nested cylinders which is close to the MICROSCOPE design. In this case we evaluate the corresponding fifth force on a test body inside the satellite. This analysis clarifies previous claims on the detectability of the chameleon force by space-borne experiments.