Generalized Blind Spots for Dark Matter Direct Detection in the 2HDM

TL;DR

This paper explores regions in the 2HDM parameter space where dark matter detection signals are suppressed, revealing new blind spots that expand the viable models without hindering early Universe annihilation processes.

Contribution

It derives analytical expressions for dark matter-Higgs couplings in the 2HDM, identifying novel blind spots that do not require cancellations and thus significantly enlarge the allowed parameter space.

Findings

Blind spots can occur without cancellations between contributions.

Allowed parameter space for dark matter models is significantly increased.

Efficient early Universe annihilation processes remain unaffected in blind spots.

Abstract

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.