Excluding the Light Dark Matter Window of a 331 Model Using LHC and Direct Dark Matter Detection Data

Abstract: We sift the impact of the recent Higgs precise measurements, and recent dark matter direct detection results, on the dark sector of an electroweak extension of the Standard Model that has a complex scalar as dark matter. We find that in this model the Higgs decays with a large branching ratio into dark matter particles, and charged scalars when these are kinematically available, for any coupling strength differently from the so called Higgs portal. Moreover, we compute the abundance and spin-independent WIMP-nucleon scattering cross section, which are driven by the Higgs and $Z^{\prime}$ boson processes. We decisively exclude the $1-500$~GeV dark matter window and find the most stringent lower bound in the literature on the scale of symmetry breaking of the model namely $10$~TeV, after applying the LUX-2013 limit. Interestingly, the projected XENON1T constraint will be able to rule out the entire $1$~GeV-$1000$~GeV dark matter mass range. Lastly, for completeness, we compute the charged scalar production cross section at the LHC and comment on the possibility of detection at current and future LHC runnings.