An i2HDM Strongly Coupled to a non-Abelian Vector Resonance

Abstract

We study the possibility of a Dark Matter candidate having its origin in an extended Higgs sector which, at least partially, is related to a new strongly interacting sector. More concretely, we consider an i2HDM (i.e. a Type-I Two Higgs Doublet Model supplemented with a Z_2 under which the non-standard scalar doublet is odd) based on the gauge group SU(2)_1 x SU(2)_2 x U(1)_Y. We assume that one of the scalar doublets and the standard fermion transform non-trivially under SU(2)_1 while the second doublet transforms under SU(2)_2. Our main hypothesis is that standard sector is weakly coupled while the gauge interactions associated to the second group is characterized by a large coupling constant. We explore the consequences of this construction for the phenomenology of the Dark Matter candidate and we show that the presence of the new vector resonance reduces the relic density saturation region, compared to the usual i2DHM, in the high Dark Matter mass range. In the collider side, we argue that the mono-Z production is the channel which offers the best chances to manifest the presence of the new vector field. We study the departures from the usual i2HDM predictions and show that the discovery of the heavy vector at the LHC is challenging even in the mono-$Z$ channel since the typical cross sections are of the order of 10^{-2} fb.