A Compendium of Chameleon Constraints
  The chameleon model is a scalar field theory with a screening mechanism that
explains how a cosmologically relevant light scalar can avoid the constraints
of intra-solar-system searches for fifth-forces. The chameleon is a popular
dark energy candidate and also arises in $f(R)$ theories of gravity. Whilst the
chameleon is designed to avoid historical searches for fifth-forces it is not
unobservable and much effort has gone into identifying the best observables and
experiments to detect it. These results are not always presented for the same
models or in the same language, a particular problem when comparing
astrophysical and laboratory searches making it difficult to understand what
regions of parameter space remain. Here we present combined constraints on the
chameleon model from astrophysical and laboratory searches for the first time
and identify the remaining windows of parameter space. We discuss the
implications for cosmological chameleon searches and future small-scale probes.
