Direct detection portals for self-interacting dark matter

Abstract

Dark matter self-interactions can affect the small scale structure of the Universe, reducing the central densities of dwarfs and low surface brightness galaxies in accord with observations. From a particle physics point of view, this points toward the existence of a 1 − 100 MeV particle in the dark sector that mediates self-interactions. Since mediator particles will generically couple to the Standard Model, direct detection experiments provide sensitive probes of self-interacting dark matter. We consider three minimal mechanisms for coupling the dark and visible sectors: photon kinetic mixing, Z boson mass mixing, and the Higgs portal. Self-interacting dark matter motivates a new benchmark paradigm for direct detection via momentum-dependent interactions, and ton-scale experiments will cover astrophysically motivated parameter regimes that are unconstrained by current limits. Direct detection is a complementary avenue to constrain velocity-dependent self-interactions that evade astrophysical bounds from larger scales, such as those from the Bullet Cluster.

Elastically Decoupling Dark Matter

“…Note that a self-scattering cross section in the 0.1 − 1 cm 2 /g range [35][36][37][38], consistent with this bound, could reconcile the N-body simulation results with the observed small-scale structure, providing an additional motivation for self-interacting DM candidates (see for instance, [40][41][42][43]). The precise relation between the elastic self-scattering and self-annihilation cross-sections is model-dependent.…”

Pseudo-majoron as light mediator of singlet scalar dark matter

“…It mixes with the SM Higgs boson only in one loop, and this mixing may be arbitrarily small because it is not needed for it to decay as in any other model of a light scalar mediator [5]. This avoids the problem [6] of too large a cross section in direct-search experiments. Further, since η I decays dominantly to two neutrinos, it avoids the problem [7,8] of too much disruption to the cosmic microwave background (CMB) if it decays to electrons or photons as in all other models of a light scalar mediator.…”

“…e − e + , would disturb the CMB, and because of the large Sommerfeld enhancement [11] for late-time decays, this effect would rule out [8] any selfinteracting dark matter with s-wave annihilation which is strong enough to address the small-scale problems of structure formation. There is also an important constraint [6] from direct-search experiments. For m χ 0 ∼ 100 GeV, the non-observation of dark matter so far places a bound on the η I − h mixing, which makes the η I lifetime too long to accommodate the success of the standard BBN.…”

New scotogenic model of neutrino mass with U(1)D gauge interaction

“…To reconcile the theoretical prediction with the present astronomical observation of the halos of dwarf galaxies, a rather large cross section per unit DM mass ∼ 1 cm 2 /g is required, and may be achieved [13,14] Finally, additional insight into DM candidates in our scenario may come from direct detection experiments. The current XENON100 limits [15] are already sensitive to very small couplings corresponding to the mixing of the dark-force carriers with the appropriate SM bosons.…”