Abstract

Self interacting scalar fields coupled to matter, known as chameleon fields, can explain the accelerating expansion of the universe while evading current fifth force constraints. In this talk we review chameleon cosmology and discuss the observable effects of such fields for experiments in space and on earth. In particular we will see how strongly coupled chameleons open up the possibility for testing a large range of parameter space in table top type experiments on earth. The GammeV experiment, in its current configuration, is a search for cosmologically interesting chameleons that couple to photons as well as to baryonic matter. Chameleons generated through electromagnetic interactions, in a closed chamber containing a magnetic field, will remain confined to that chamber due to their matter interactions. These particles will gradually decay to photons, producing an “afterglow’’ effect which is a unique signature of chameleons.