Particle Theory Seminar: Jiji Fan, Brown University, “Ultralight repulsive dark matter”

Ultralight scalar dark matter with mass at or below the eV scale and pressure from repulsive self-interaction could form a Bose-Einstein condensate in the early Universe and maybe in galaxies as well. It has been suggested to be a possible solution to the cusp/core problem or even to explain MOND phenomenology. I will investigate this possibility from the particle physics point of view. To protect its mass, the scalar dark matter is identified as a pseudo Nambu-Goldstone boson (pNGB). I will demonstrate that it is non-trivial, usually with tuning, to have a pNGB model with repulsive self-interactions.