Generalized Blind Spots for Dark Matter Direct Detection in the 2HDM
  In this paper we study the presence of generalized blind spots, i.e. regions
of the parameter space where the spin-independent cross section for dark matter
direct detection is suppressed, in the context of a generic 2HDM and a minimal
fermionic Higgs-portal dark sector. To this end, we derive analytical
expressions for the couplings of the dark matter to the light and heavy
Higgses, and thus for the blind spot solutions. Unlike the case of a standard
Higgs sector, blind spots can occur even without a cancellation between
different contributions, while keeping unsuppressed and efficient the
annihilation processes in the early Universe involving Higgs states. As a
consequence, the allowed parameter space is dramatically enhanced.
