Searching for Chameleon Dark Energy with Mechanical Systems

TL;DR

This paper investigates the potential of near-term mechanical experiments, like levitated microspheres and torsion balances, to detect or constrain chameleon dark energy models that introduce a fifth force, providing analytical tools and experimental guidance.

Contribution

It offers analytical expressions linking chameleon model parameters to experimental variables and demonstrates current experiments can test significant parts of the chameleon parameter space.

Findings

Current experiments can rule out large portions of chameleon parameter space.

Analytical expressions relate experimental variables to chameleon model parameters.

Guidance for future experiments targeting well-motivated chameleon models.

Abstract

A light scalar field framework of dark energy, sometimes referred to as quintessence, introduces a fifth force between normal matter objects. Screening mechanisms, such as the chameleon model, allow the scalar field to be almost massless on cosmological scales while simultaneously evading laboratory constraints. We explore the ability of mechanical systems available in the near term to directly detect the fifth force associated with chameleon dark energy. We provide analytical expressions for the weakest accessible chameleon model parameters in terms of experimentally tunable variables and apply our analysis to two mechanical systems: levitated microspheres and torsion balances, showing that the current generation of these experiments have the sensitivity to rule out a significant portion of the proposed chameleon parameter space. We also indicate regions of theoretically well-motivated chameleon parameter space to guide future experimental work.