In light of the recent neutrino experiment results from the Daya Bay and RENO Collaborations, we study phenomenology of neutrino mixing angles in the type III seesaw model with a discrete A 4×Z 2 symmetry, whose spontaneously breaking scale is much higher than the electroweak scale. At tree level, the tri-bimaximal (TBM) form of the lepton mixing matrix can be obtained from leptonic Yukawa interactions in a natural way. We introduce all possible effective dimension-five operators, invariant under the standard model gauge group and A 4×Z 2, and explicitly show that they induce a deviation of the lepton mixing from the TBM mixing matrix, which can explain a large mixing angle θ 13 together with small deviations of the solar and atmospheric mixing angles from the TBM. Two possible scenarios are investigated, by taking into account either negligible or sizable contributions from the light charged lepton sector to the lepton mixing matrix. Especially it is found in the latter scenario that all the neutrino experimental data, including the recent best-fit value of θ 13= 8.68°, can be accommodated. The leptonic CP violation characterized by the Jarlskog invariant J CP has a nonvanishing value, indicating a signal of maximal CP violation.
|Journal||Physical Review D - Particles, Fields, Gravitation and Cosmology|
|Publication status||Published - 2012 Jul 6|
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics
- Physics and Astronomy (miscellaneous)