Theory HEP Seminar

Hunting Chameleons

Anne Davis

Cambridge University

The observed acceleration of the universe today can be explained by dark energy; the energy density of a very light scalar field which dominates today. If the scalar field couples to ordinary matter it will produce deviations from general relativity in the solar system. The chameleon mechanism is a way of reconciling solar systems tests of gravity and the acceleration of the universe today. The mass of the chameleon depends on its environment. I will introduce the chameleon mechanism and discuss ways of detecting chameleons in the laboratory and in cosmology.