The T2K Indication of Relatively Large theta_13 and a Natural Perturbation to the Democratic Neutrino Mixing Pattern

Understand

The T2K Collaboration has recently reported a remarkable indication of the \nu_\mu -> \nu_e oscillation which is consistent with a relatively large value of \theta_{13} in the three-flavor neutrino mixing scheme.

• We show that it is possible to account for such a result of \theta_{13} by introducing a natural perturbation to the democratic neutrino mixing pattern, without or with CP violation.
• A testable correlation between \theta_{13} and \theta_{23} is predicted in this ansatz.
• We also discuss the Wolfenstein-like parametrization of neutrino mixing, and comment on other possibilities of generating sufficiently large \theta_{13} at the electroweak scale.