Discrete flavour symmetries in light of T2K

We show that a non-vanishing angle θ13 of order 0.1 can be predicted in the framework of discrete flavour symmetries. We assume that left-handed leptons transform as triplets under a group Gf which is broken in such a way that neutrino and charged lepton sectors remain invariant under the subgroups Gν and Ge of Gf, respectively. In this limit mixing angles and the Dirac CP violating phase δCP are determined. By choosing Gf=Δ(6n2) (n=4,8), Gν=Z2×Z2 and Ge=Z3 we find sin2θ13=0.045(0.011) for n=4(8). At the same time θ23 and θ12 remain close to their experimental best fit values, particularly in the case n=8, where sin2θ23≈0.424 and sin2θ12≈0.337. δCP is predicted to be 0 or π so that CP is conserved in our examples.