  In this paper, we provide a set of Hermitian interactions for quantum fields
based on Elko, considering the recent achievements concerning the most general
form of singular spinors and Wigner degeneracy. We consider Hermiticity and
renormalizability a criterion to define the derivative Elko-Higgs interaction
as the suitable candidate for a dark coupling. Then, the free parameters of the
model are fixed by cosmological constraints on the dark matter abundance,
bounds on the Higgs invisible decays, and limits on the electron-dark matter
scattering mediated by the Higgs.
