Title：A Scalar & Fermion Two-component SIMP Dark Matter Model
Time：2022/05/23 (Mon.) 13:30
Place：Online (Google Meet)
Link：https://meet.google.com/wnc-izsa-anv

Abstract:
In this talk, I will show for the first time a two-component strongly interacting massive particles (SIMP) dark matter (DM) model, where a complex scalar and a vector-like fermion play the role of the SIMP DM candidates. These two particles are stable due to an accidental Z_4 symmetry after the breaking of a U(1)_D gauge symmetry. By introducing one extra complex scalar as a mediator between the SIMP particles, this model can have 3 to 2 processes that determine the DM relic density. On the other hand, the SIMP DM particles can maintain kinetic equilibrium with the thermal bath until the DM freeze-out temperature via the U(1)_D gauge couplings. Most importantly, we find an unavoidable two-loop induced 2 to 2 process tightly connecting to the 3 to 2 process that would redistribute the SIMP DM number densities after the chemical freeze-out of DM. Moreover, this redistribution would significantly modify the predictions of the self-interacting cross-section of DM compared with other SIMP models. It is crucial to include the two-loop induced 2 to 2 annihilations to obtain the correct DM phenomenology.