Non-sterile electroweak-scale right-handed neutrinos and the dual nature of the 125-GeV scalar

Can, and under which conditions, the 125-\gev SM-like scalar with the signal strengths for its decays into $W^{+}W^{-}$, $ZZ$, $\gamma \gamma$, $b \bar{b}$ and $\tau \bar{\tau}$ being consistent with experiments be accommodated in models that go beyond the Standard Model? Is it truly what it appears to be, namely the SM Higgs boson, or could it be quite different? A minimal extension of the original electroweak-scale right-handed neutrino model, in which right-handed neutrinos naturally obtain electroweak-scale masses, shows a scalar spectrum which includes either the 125-\gev SM-like scalar or a scalar which is quite {\em unlike} that of the Standard Model, both of which possessing signal strengths compatible with experiment. In other words, the 125-\gev scalar could be an {\em impostor}.Comment: 36 double-column pages, 13 Figures, 9 Tables. Typos corrected. Version to appear in Nuclear Physics