A multi-component SIMP model with $U(1)_X \rightarrow Z_2 \times Z_3$

Multi-component dark matter scenarios are studied in the model with U(1)$_{X}$ dark gauge symmetry that is broken into its product subgroup Z$_{2}$ × Z$_{3}$ á la Krauss-Wilczek mechanism. In this setup, there exist two types of dark matter fields, X and Y, distinguished by different Z$_{2}$ × Z$_{3}$ charges. The real and imaginary parts of the Z$_{2}$-charged field, X$_{R}$ and X$_{I}$, get different masses from the U(1)$_{X}$ symmetry breaking. The field Y, which is another dark matter candidate due to the unbroken Z$_{3}$ symmetry, belongs to the Strongly Interacting Massive Particle (SIMP)-type dark matter. Both X$_{I}$ and X$_{R}$ may contribute to Y’s 3 → 2 annihilation processes, opening a new class of SIMP models with a local dark gauge symmetry. Depending on the mass difference between X$_{I}$ and X$_{R}$, we have either two-component or three-component dark matter scenarios. In particular two- or three-component SIMP scenarios can be realised not only for small mass difference between X and Y, but also for large mass hierarchy between them, which is a new and unique feature of the present model. We consider both theoretical and experimental constraints, and present four case studies of the multi-component dark matter scenarios.