Dirac dark matter with a charged mediator: a comprehensive one-loop
  analysis of the direct detection phenomenology
  We analyze the direct detection signals of a toy model consisting of a Dirac
dark matter particle which couples to one Standard Model fermion via a scalar
mediator. For all scenarios, the dark matter particle scatters off nucleons via
one loop-induced electromagnetic and electroweak moments, as well as via the
one-loop exchange of a Higgs boson. Besides, and depending on the details of
the model, the scattering can also be mediated at tree level via the exchange
of the scalar mediator or at one loop via gluon-gluon interactions. We show
that, for thermally produced dark matter particles, the current limits from the
LUX experiment on these scenarios are remarkably strong, even for dark matter
coupling only to leptons. We also discuss future prospects for XENON1T and
DARWIN and we argue that multi-ton xenon detectors will be able to probe
practically the whole parameter space of the model consistent with thermal
production and perturbativity. We also discuss briefly the implications of our
results for the dark matter interpretation of the Galactic GeV excess.
