Isospin-violating dark-matter-nucleon scattering via two-Higgs-doublet-model portals

TL;DR

This paper explores how multi-Higgs models, particularly Type II two-Higgs-doublet models, can facilitate isospin-violating dark matter interactions with nucleons, and identifies viable light scalar dark matter candidates consistent with experimental constraints.

Contribution

It demonstrates the possibility of maximal isospin violation in DM-nucleon interactions mediated by additional Higgs bosons in multi-Higgs models, independent of DM nature.

Findings

Maximal isospin violation achievable with appropriate Higgs-quark couplings.

Identification of the 125 GeV Higgs as either h or H in the model.

Viable light scalar DM candidate with correct relic density and detection limits.

Abstract

We show that in a multi-Higgs model in which one Higgs fits the LHC 125 GeV state, one or more of the other Higgs bosons can mediate DM-nucleon interactions with maximal DM isospin violation being possible for appropriate Higgs-quark couplings, independent of the nature of DM. We then consider the explicit example of a Type II two-Higgs-doublet model, identifying the h or H as the 125 GeV state while the H or h, respectively, mediates DM-nucleon interactions. Finally, we show that if a stable scalar, S, is added then it can be a viable light DM candidate with correct relic density while obeying all direct and indirect detection limits.