Speaker
Description
Strongly Interacting Massive Particles (SIMPs) provide an intriguing alternative to conventional collisionless dark matter (CDM) scenarios, particularly in light of tensions between CDM predictions and observations on small astrophysical scales. In SIMP models, the observed dark matter relic abundance is generated through self-annihilation processes such as $3 \to 2$ or $4 \to 2$, involving only dark sector particles. However, these processes can overheat the dark sector and jeopardise structure formation. This issue can be resolved if the DM particles are in kinetic equilibrium with lighter particles, which redshifts similar to radiation during DM freezeout, either in the SM or the dark sector. In conventional SIMP models, the interactions responsible for kinetic equilibrium are often related by crossing symmetry to pair-annihilation processes, inevitably inducing sizable dark matter annihilation into radiation. This leads to strong constraints on the allowed parameter space. In this talk, I will introduce a novel mechanism in which dark matter–radiation scattering and annihilation are governed by different combinations of parameters. I will show that it can be realized in new physics models, and then discuss their potential detections.