Inelastic Signatures of Electroweak Dark Matter

Abstract

Minimal dark matter extended to include a Majorana and a Dirac multiplet coupled through the Higgs --- the HC-MDM model --- provides a compelling and predictive framework. We show that in certain limits of this model, the mass splitting and the inelastic interaction are representation-independent, while the thermal-relic masses are representation-dependent. We then show that this model can account for the high-energy recoil event recently reported by LUX-ZEPLIN (LZ) while also respecting thermal-relic, elastic-scattering, and solar-capture constraints. Generic inelastic DM models do not connect all these tests and generic Higgsino models do not survive them.

Comments: 7 pages, 3 figures. Substantially improved version with expanded discussion, updated phenomenology, and additional consistency checks