Phenomenology of a TeV right-handed neutrino and the dark matter model

In a model of a TeV right-handed (RH) neutrino by Krauss, Nasri, and Trodden, the sub-eV scale neutrino masses are generated via a three-loop diagram with the vanishing seesaw mass forbidden by a discrete symmetry, and the TeV mass RH neutrino is simultaneously a novel candidate for cold dark matter. However, we show that with a single RH neutrino it is not possible to generate two mass-square differences as required by the oscillation data. We extend the model by introducing one more TeV RH neutrino and show that it is possible to satisfy the oscillation pattern within the modified model. After studying in detail the constraints coming from the dark matter, lepton flavor violation, the muon anomalous magnetic moment, and the neutrinoless double beta decay, we explore the parameter space and derive predictions of the model. Finally, we study the production and decay signatures of the TeV RH neutrinos at TeV e(+)e(-)/mu(+)mu(-) colliders.