Physics (Internal)

The SIMPlest Miracle

This event is part of the HET Seminar Series.

Abstract: I will present a new paradigm for achieving thermal relic dark matter. The mechanism arises when a nearly secluded dark sector is thermalized with the Standard Model after reheating. The freezeout process is a number-changing 3-to-2 annihilation of strongly-interacting-massive-particles (SIMPs) in the dark sector, and points to sub-GeV dark matter. The couplings to the visible sector, necessary for maintaining thermal equilibrium with the Standard Model, imply measurable signals that will allow coverage of a significant part of the parameter space with future indirect- and direct-detection experiments and via direct production of dark matter at colliders. Moreover, 3-to-2 annihilations typically predict sizable 2-to-2 self-interactions which naturally address the ‘core vs. cusp’ and ‘too-big-to-fail’ small structure problems. I will describe a class of theories in which the dark matter is a pion in a QCD-like hidden sector, while the Wess-Zumino-Witten term generates the 5-point interaction of the 3-to-2 process.