Two Higgs Doublet Dark Matter Portal

TL;DR

This paper explores a fermionic dark matter model with Higgs portal interactions via a Two Higgs Doublet Model, analyzing constraints and parameter space to achieve correct relic density while satisfying experimental bounds.

Contribution

It introduces a detailed analysis of a Two Higgs Doublet Model with fermionic dark matter, highlighting the richer parameter space beyond simplified single scalar mediator models.

Findings

Identifies viable parameter regions satisfying all experimental constraints.

Demonstrates the model's potential to produce correct relic density.

Shows the importance of scalar mixing in dark matter interactions.

Abstract

We study a fermionic dark matter model in which the interaction of the dark and visible sectors is mediated by Higgs portal type couplings. Specifically, we consider the mixing of a dark sector scalar with the scalars of a Two Higgs Doublet Model extension of the Standard Model. Given that scalar exchange will result in a spin-independent dark matter-nucleon scattering cross section, such a model is potentially subject to stringent direct detection constraints. Moreover, the addition of new charged scalars introduce non-trivial flavour constraints. Nonetheless, this model allows more freedom than a standard Higgs portal scenario involving a single Higgs doublet, and much of the interesting parameter space is not well approximated by a Simplified Model with a single scalar mediator. We perform a detailed parameter scan to determine the mass and coupling parameters which satisfy direct detection, flavour, precision electroweak, stability, and perturbativity constraints, while still producing the correct relic density through thermal freezeout.