Resonant SIMP dark matter

We consider a resonant SIMP dark matter in models with two singlet complex scalar fields charged under a local dark U(1)DU(1)D. After the U(1)DU(1)D is broken down to a Z5Z5 discrete subgroup, the lighter scalar field becomes a SIMP dark matter which has the enhanced 3→23→2 annihilation cross section near the resonance of the heavier scalar field. Bounds on the SIMP self-scattering cross section and the relic density can be fulfilled at the same time for perturbative couplings of SIMP. A small gauge kinetic mixing between the SM hypercharge and dark gauge bosons can be used to make SIMP dark matter in kinetic equilibrium with the SM during freeze-out.