Weakly interacting dark matter particle of a minimal technicolor theory

Abstract

We consider the possibility that a massive fourth family neutrino, predicted by a recently proposed minimal technicolor theory, could be the source of the dark matter in the Universe. The model has two techniflavors in the adjoint representation of a SU(2) techicolor gauge group and its consistency requires the existence of a fourth family of leptons. By a suitable hypercharge assignment the techniquarks together with the new leptons look like a conventional fourth standard model family. We show that the new (Majorana) neutrino $N$ can be the dark matter particle if ${m}_{N}\ensuremath{\sim}100--500\text{ }\text{ }\mathrm{GeV}$ and the expansion rate of the Universe at early times is dominated by an energy component scaling as ${\ensuremath{\rho}}_{\ensuremath{\phi}}\ensuremath{\sim}{a}^{\ensuremath{-}6}$ (kination), with ${\ensuremath{\rho}}_{\ensuremath{\phi}}/{\ensuremath{\rho}}_{\mathrm{rad}}\ensuremath{\sim}{10}^{\ensuremath{-}6}$ during the nucleosynthesis era.