Effective scalar four-fermion interaction for Ge-phobic exothermic dark matter and the CDMS-II Silicon excess

Understand

We discuss within the framework of effective four-fermion scalar interaction the phenomenology of a Weakly Interacting Massive Particle (WIMP) Dirac Dark Matter candidate which is exothermic (i.e.

• is metastable and interacts with nuclear targets down-scattering to a lower-mass state) and $Ge$-phobic (i.e.
• whose couplings to quarks violate isospin symmetry leading to a suppression of its cross section off Germanium targets).
• We discuss the specific example of the CDMS-II Silicon three-candidate effect showing that a region of the parameter space of the model exists where WIMP scatterings can explain the excess in compliance with other experimental constraints, while at the same time the Dark Matter particle can have a thermal relic density compatible with observation.