Dark energy fifth forces in torsion pendulum experiments

TL;DR

This paper develops an approximation method to compute chameleon scalar field fifth forces in torsion pendulum experiments, extending existing constraints and forecasting the potential of future experiments to exclude many models.

Contribution

It introduces a simple approximation for chameleon fifth forces in torsion pendulum setups, enabling broader constraints and future experimental forecasts.

Findings

Approximation agrees with existing constraints on quartic chameleon models.

Extends constraints to a wider range of models.

Next-generation experiments could exclude many quantum-stable models.

Abstract

The chameleon scalar field is a matter-coupled dark energy candidate whose nonlinear self-interaction partially screens its fifth force at laboratory scales. Nevertheless, small-scale experiments such as the torsion pendulum can provide powerful constraints on chameleon models. Here we develop a simple approximation for computing chameleon fifth forces in torsion pendulum experiments such as Eot-Wash. We show that our approximation agrees well with published constraints on the quartic chameleon, and we use it to extend these constraints to a much wider range of models. Finally, we forecast the constraints which will result from the next-generation Eot-Wash experiment, and show that this experiment will exclude a wide range of quantum-stable models.