Discrete Flavour Symmetries in Light of T2K

Understand

We show that a non-vanishing angle theta_13 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 G_f which is broken in such a way that neutrino and charged lepton sectors remain invariant under the subgroups G_nu and G_e of G_f, respectively.
• In this limit mixing angles and the Dirac CP violating phase delta_CP are determined.
• By choosing G_f=Delta(6 n^2) (n=4,8), G_nu=Z_2 x Z_2 and G_e=Z_3 we find sin^2 theta_13=0.045(0.011) for n=4(8).