Searching for Chameleon Dark Energy with Mechanical Systems
  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.
