Scotogenic model for co-bimaximal mixing

Abstract

We present a scotogenic model, i.e. a one-loop neutrino mass model with dark right-handed neutrino gauge singlets and one inert dark scalar gauge doublet $\eta$, which has symmetries that lead to co-bimaximal mixing, i.e. to an atmospheric mixing angle ${\theta }_{23}=45^{\circ }$ and to a $CP$-violating phase $\delta =\pm \pi /2$, while the mixing angle ${\theta }_{13}$ remains arbitrary. The symmetries consist of softly broken lepton numbers $L_{\alpha }$ ($\alpha =e,\mu ,\tau$), a non-standard $CP$ symmetry, and three $Z_2$ symmetries. We indicate two possibilities for extending the model to the quark sector. Since the model has, besides $\eta$, three scalar gauge doublets, we perform a thorough discussion of its scalar sector. We demonstrate that it can accommodate a Standard Model-like scalar with mass $125\mathrm{GeV}$, with all the other charged and neutral scalars having much higher masses.

Comments: v2 - 23 pages, 5 figures, minor changes requested by referee