An asymmetric SIMP dark matter model

Abstract

In this paper, we construct the first asymmetric strongly interacting massive particles (SIMP) dark matter (DM) model, where a new vector-like fermion and a new complex scalar both having nonzero chemical potentials can be asymmetric DM particles. After the spontaneous breaking of a U(1)D dark gauge symmetry, these two particles can have accidental ℤ4 charges making them stable. By adding one more complex scalar as a mediator between the SIMP DM, the relic density of DM is determined by 3 → 2 and two-loop induced 2 → 2 annihilations in this model. On the other hand, the SIMP DM can maintain kinetic equilibrium with the thermal bath until the DM freeze-out temperature via the new gauge interaction. Interestingly, this model can have a bouncing effect on DM, whereby the DM number density rises after the chemical freeze-out of DM. With this effect, the prediction of the DM self-interacting cross section in this model can be consistent with astrophysical observations, and the ratio of the DM energy density to the baryonic matter energy density can be explained by primordial asymmetries. We also predict the DM-electron elastic scattering cross section that can be used to test this model in future projected experiments.

Exponential Enhancement of Dark Matter Freezeout Abundance

“…1 initially but "bounces" to a different (exponentially rising) equilibrium distribution while in thermal equilibrium. Such nontrivial behavior of the number density of a species in thermal equilibrium had previously also been observed in earlier works [16][17][18][19], although the associated mechanism was not discussed in detail. This note is only a short summary of the main ideas presented in [15]; the interested reader is referred to that paper for further details.…”

Fermion singlet dark matter in a pseudoscalar dark matter portal

“…Although this bouncing effect in the yield of some specie has been already observed in the context of thermal DM, see e.g. [6,7,8], the connection of this yield feature with indirect detection has only been worked in [5].…”

Bouncing pNGB dark matter via a fermion dark matter

“…Although this bouncing effect in the yield of some species has been already observed in the context of thermal DM, see e.g. [8][9][10][11], the connection of this feature with indirect detection has only been worked out in [7].…”