Nonstandard Yukawa Couplings and Higgs Portal Dark Matter

TL;DR

This paper explores how non-standard light-quark Yukawa couplings can significantly enhance Higgs-portal dark matter detection rates, providing potential new bounds on these couplings from dark matter experiments.

Contribution

It analyzes the impact of non-standard Yukawa couplings on dark matter phenomenology and identifies scenarios where detection rates could increase substantially.

Findings

Dark matter scattering rate can increase by up to four orders of magnitude.

Enhancement in scattering rate of about an order of magnitude is possible.

Discovery of Higgs-portal dark matter could constrain light-quark Yukawa couplings.

Abstract

We study the implications of non-standard Higgs Yukawa couplings to light quarks on Higgs-portal dark matter phenomenology. Saturating the present experimental bounds on up-quark, down-quark, or strange-quark Yukawa couplings, the predicted direct dark matter detection scattering rate can increase by up to four orders of magnitude. The effect on the dark matter annihilation cross section, on the other hand, is subleading unless the dark matter is very light -- a scenario that is already excluded by measurements of the Higgs invisible decay width. We investigate the expected size of corrections in multi-Higgs-doublet models with natural flavor conservation, the type-II two-Higgs-doublet model, the Giudice-Lebedev model of light quark masses, minimal flavor violation new physics models, Randall-Sundrum, and composite Higgs models. We find that an enhancement in the dark matter scattering rate of an order of magnitude is possible. Finally, we point out that a discovery of Higgs-portal dark matter could lead to interesting bounds on the light-quark Yukawa couplings.