Maximal CP violation in lepton mixing from a model with Δ(27) flavour symmetry

Abstract

We propose a simple mechanism which enforces $\left| {{U_{\mu j}}} \right| = \left| {{U_{\tau j}}} \right|\forall j = 1,2,3$ in the lepton mixing matrix U. This implies maximal atmospheric neutrino mixing and a maximal CP-violating phase but does not constrain the reactor mixing angle θ 13. We implement the proposed mechanism in two renormalizable seesaw models which have features strongly resembling those of models based on a flavour symmetry group Δ(27). Among the predictions of the models, there is a determination, although ambiguous, of the absolute neutrino mass scale, and a stringent correlation between the absolute neutrino mass scale and the effective Majorana mass in neutrinoless double-beta decay.