Speaker: Zach Bogorad (Stanford)
Title: Constraints on Long-Range Interactions Between Dark Matter and the Standard Model
Room: 3024
Host: Hsin-Chia Cheng
Abstract: There are a variety of experimental and astrophysical constraints on non-gravitational interactions of dark matter with the Standard Model, but most assume that such interactions are short-ranged, with individual dark matter particles interacting with individual Standard Model particles. It is also possible, however, for dark matter to have weak but long-ranged interactions with the Standard Model, potentially resulting in collective interaction effects. I will present a variety of constraints on such interactions, primarily for forces with ranges of O(1 mpc) or more, and emphasizing that the parameter space available for them can vary considerably depending on the precise nature of the interaction. I will focus especially on constraints arising from dynamical friction, the gradual transfer of kinetic energy from stars to dark matter halos, which is extremely slow when mediated exclusively by gravity but can be significant in the presence of new interactions. In particular, observations of stellar velocities in the Segue 1 ultrafaint dwarf galaxy constrain many classes of new forces with ranges above O(1 mpc) to be no stronger than O(100) times gravity, improving on existing bounds at these ranges by several orders of magnitude.
