Grant: Subatomic Physics Envelope - Individual

The experimental evidence for dark matter is overwhelming, and yet the particle nature of dark matter, and the connection to the Standard Model of particle physics, remains a mystery. The uncertainty in the dark matter particle mass is many orders of magnitude, and there is no constraint on the spin of the dark matter particle, or its nature as a boson or fermion. These questions can be mapped onto the dynamics of dark matter in the very early universe, namely the physics responsible for setting the present day dark matter abundance, as well as the dynamics of dark matter in galaxies, and hence the properties of present day dark matter halos. These two regimes, namely the extreme high energy "cosmological collider" in the early universe and the high density environment of dark matter halos, are complementary testing grounds for dark matter models, and help circumscribe the set of models consistent with data. This has implications for particle physics experiments, which are sensitive to the mass, spin, and interactions, of dark matter. My approach to uncovering the particle physics of dark matter will be to be study these extreme environments, expand our notion of models that are possible and are consistent with data, and make predictions for particle physics experiments. In particular, I plan to investigate the signature of these models in varying observational windows, and to study the cosmological signatures of axions, including the role of axion-like particles in measurements of the expansion rate of the universe. This research program synthesizes different parameter and model regimes and their implications for particle physics experiments. It builds toward a long-term vision of ruling-in or ruling-out broad classes of dark matter models, such as the extreme ends of the mass range (ultralight and superheavy) or high spin particles.