Talks

Experiments have ruled out unit-strength scalar-mediated fifth forces on scales ranging from 0.1 mm to 10,000 AU. However, allowing the scalar to have a quartic self-interaction weakens these constraints considerably. This weakening is due to the "chameleon mechanism", which gives the scalar field an effective mass that depends on the local matter density. I will describe the chameleon mechanism and discuss experimental constraints on self-interacting scalar fields. In particular, I will compare the chameleon-mediated self interaction to constraints from the Eot-Wash experiment, at the University of Washington, which comes closest to detecting such a scalar field today. It will be shown that a quartic self interaction of unit strength is just out of reach of the current Eot-Wash experiment, but will be readily visible to their next-generation instrument.