Common Origin of mu-tau and CP Breaking in Neutrino Seesaw, Baryon Asymmetry, and Hidden Flavor Symmetry

Hong-Jian He, Fu-Rong Yin

Published 2011-04-14, updated 2012-04-17Version 4

We conjecture that all CP violations (both Dirac and Majorana types) arise from a common origin in neutrino seesaw. With this conceptually attractive and simple conjecture, we deduce that mu-tau breaking shares the common origin with all CP violations. We study the common origin of mu-tau and CP breaking in the Dirac mass matrix of seesaw Lagrangian (with right-handed neutrinos being mu-tau blind), which uniquely leads to inverted mass-ordering of light neutrinos. We then predict a very different correlation between the two small mu-tau breaking observables theta_{13}-0 and theta_{23}-45, which can saturate the present experimental upper limit on theta_{13}. This will be tested against our previous normal mass-ordering scheme by the on-going oscillation experiments. We also analyze the correlations of theta_{13} with Jarlskog invariant and neutrinoless double-beta-decay observable. From the common origin of CP and mu-tau breaking in the neutrino seesaw, we establish a direct link between the low energy CP violations and the cosmological CP violation for baryon asymmetry. With these we further predict a lower bound on theta_{13}, supporting the on-going probes of theta_{13} at Daya Bay, Double Chooz and RENO experiments. Finally, we analyze the general model-independent Z_2 x Z_2 symmetry structure of the light neutrino sector, and map it into the seesaw sector, where one of the Z_2's corresponds to the mu-tau symmetry and another the hidden symmetry Z_2^s (revealed in our previous work) which dictates the solar mixing angle \theta_{12}. We derive the physical consequences of this Z_2^s and its possible partial violation in the presence of mu-tau breaking (without or with neutrino seesaw), regarding the theta_{12} determination and the correlation between mu-tau breaking observables.