Speaker
Description
We study a two-component dark matter model in which the dark matter particles are a
singlet fermion (ψ) and a singlet scalar (S), both stabilized by a single Z4 symmetry. The
model is remarkably simple, with its phenomenology determined by just five parameters:
the two dark matter masses and three dimensionless couplings. In fact, S interacts with the
Standard Model particles via the usual Higgs-portal, whereas ψ only interacts directly with
S, via the Yukawa terms ψc(ys + ypγ5)ψ S. We consider the two possible mass hierarchies
among the dark matter particles, MS < Mψ and Mψ < MS , and numerically investigate the
consistency of the model with current bounds. For dark matter masses below 1.3 TeV or so,
we find that the model not only is compatible with all known constraints, but that it also
gives rise to observable signals in future dark matter experiments. Interestingly, both dark
matter particles may be observed in direct detection experiments while the most relevant
indirect detection channel is due to the annihilation of ψ. We also argue that this setup can
be extended to other ZN symmetries and additional dark matter particles.
