Speaker
Description
Sub-MeV dark matter remains relatively unconstrained by direct detection, and several well-motivated candidates in this mass range have aroused great interest. Electron recoil experiments have been proposed as a technique to detect such a light particle, but little is known about the extent of cosmological restrictions on a light species coupled to electrons. We perform a systematic study of cosmological constraints on a light dark matter particle coupled to electrons by one of a comprehensive set of effective operators, which approximate a broad class of models with a heavy mediator. Specificially, we study constraints from primordial nucleosynthesis, the dark matter relic abundance, and the effective number of neutrino species ($N_{\mathrm{eff}}$) at CMB formation. We demonstrate the implications of our results for proposed electron recoil experiments, and highlight the regions of parameter space which may be amenable to direct detection.
