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Abstract:
In [1, 2] it has been mentioned that the Cabibbo angle θC might arise from a dihedral flavor symmetry (which is broken to different (directions of) subgroups in the up and the down quark sector). Here we construct a low energy model which incorporates this idea. The gauge group is the one of the Standard Model and D7 × Z2(aux) serves as flavor symmetry. The additional Z2(aux) is necessary in order to maintain two sets of Higgs fields, one which couples only to up quarks and another one coupling only to down quarks. We assume that D7 is broken spontaneously at the electroweak scale by vacuum expectation values of SU(2)L doublet Higgs fields. The quark masses and mixing parameters can be accommodated well. Furthermore, the potential of the Higgs fields is studied numerically in order to show that the required configuration of the vacuum expectation values can be achieved. We also comment on more minimalist models which explain the Cabibbo angle in terms of group theoretical quantities, while θ13q and θ23q vanish at leading order. Finally, we perform a detailed numerical study of the lepton mixing matrix VMNS in which one of its elements is entirely determined by the group theory of a dihedral symmetry. Thereby, we show that nearly tri-bi-maximal mixing can also be produced by a dihedral flavor group with preserved subgroups.
