Perturbative generation of theta_{13} from tribimaximal neutrino mixing

TL;DR

This paper investigates how small perturbations to the tribimaximal neutrino mixing matrix can generate the observed non-zero value of _{13}, including CP violation, and discusses a gauge model realization.

Contribution

It provides a model-independent perturbative framework to explain the non-zero _{13} from tribimaximal mixing and explores a gauge model with one-loop effects that produce such perturbations.

Findings

First-order perturbation calculations match observed _{13} values.

Perturbations can also account for solar neutrino splitting.

CP violation effects are incorporated in the perturbative approach.

Abstract

Solar and atmospheric neutrino oscillations are consistent with a tribimaximal form of the mixing matrix $U$ of the lepton sector. Exact tribimaximal mixing leads to $\theta_{13}=0$. Recent results from the Daya Bay and RENO experiments have established a non-zero value of $\theta_{13}$. Keeping the leading behaviour of $U$ as tribimaximal we perform a model-independent perturbative calculation to incorporate a non-vanishing $\theta_{13}$. We identify the nature of the perturbation matrix and consider the possibility of the solar neutrino splitting also resulting from it. We calculate up to first order in perturbation theory and evaluate the deviations proportional to $\sin \theta_{13}$ while including CP-nonconservation. Finally, we briefly discuss a gauge model where such an addition to the neutrino mass matrix arises through one-loop effects.