No Arabic abstract
A new and novel idea for a predictive neutrino mass matrix is presented, using the non-Abelian discrete symmetry A(4) and the seesaw mechanism with only two heavy neutral fermion singlets. Given the components of the one necessarily massless neutrino eigenstate, the other two massive states are automatically generated. A realistic example is discussed with predictions of a normal hierarchy of neutrino masses and maximal CP violation.
Current experimental data on neutrino mixing are very well described by TriBiMaximal mixing. Accordingly, any phenomenological parametrization of the MNSP matrix must build upon TriBiMaximal mixing. We propose one particularly natural parametrization, which we call TriMinimal. The three small deviations of the PDG angles from their TriBiMaximal values, and the PDG phase, parametrize the TriMinimal mixing matrix. As an important example of the utility of this new parametrization, we present the simple resulting expressions for the flavor-mixing probabilities of atmospheric and astrophysical neutrinos. As no foreseeable experiment will be sensitive to more than second order in the small parameters, we expand these flavor probabilities to second order.
With the latest results of a large mixing angle $theta_{13}$ for neutrinos by the T2K, MINOS and Double Chooz experiments, we find that the self-complementarity (SC) relations agree with the data in some angle-phase parametrizations of the lepton mixing matrix. There are three kinds of self-complementarity relations: (1) $vartheta_i+vartheta_j=vartheta_k=45^circ$; (2) $vartheta_i+vartheta_j=vartheta_k$; (3) $vartheta_i+vartheta_j=45^circ$ (where $i$, $j$, $k$ denote the mixing angles in the angle-phase parametrizations). We present a detailed study on the self-complementarity relations in nine different angle-phase parametrizations, and also examine the explicit expressions in reparametrization-invariant form, as well as their deviations from global fit. These self-complementarity relations may lead to new perspective on the mixing pattern of neutrinos.
It is shown that the bi-maximal solution is the only possibility to reconcile Zee-type neutrino mass matrix with three flavors to the current atmospheric and solar neutrino experimental data. The mass of the lightest neutrino, which consist mostly of $ u_{mu}$ and $ u_{tau}$, is $simeq Delta m_{odot}^2/(2sqrt{Delta m_{atm}^2})$. The related topics on Zee-type neutrino mass matrix are also discussed.
The latest experimental progress have established three kinds of neutrino oscillations with three mixing angles measured to rather high precision. There is still one parameter, i.e., the CP violating phase, missing in the neutrino mixing matrix. It is shown that a replay between different parametrizations of the mixing matrix can determine the full neutrino mixing matrix together with the CP violating phase. From the maximal CP violation observed in the original Kobayashi-Maskawa (KM) scheme of quark mixing matrix, we make an Ansatz of maximal CP violation in the neutrino mixing matrix. This leads to the prediction of all nine elements of the neutrino mixing matrix and also a remarkable prediction of the CP violating phase $delta_{rm CK}=(85.48^{+4.67(+12.87)}_{-1.80(-4.90)})^circ$ within $1sigma (3sigma)$ range from available experimental information. We also predict the three angles of the unitarity triangle corresponding to the quark sector for confronting with the CP-violation related measurements.
We build an $S_4$ model for neutrino masses and mixings based on the self-complementary (SC) neutrino mixing pattern. The SC mixing is constructed from the self-complementarity relation plus $delta_{rm CP}=-frac{pi}{2}$. We elaborately construct the model at a percent level of accuracy to reproduce the structure given by the SC mixing. After performing a numerical study on the models parameter space, we find that in the case of normal ordering, the model can give predictions on the observables that are compatible with their $3sigma$ ranges, and give predictions for the not-yet observed quantities like the lightest neutrino mass $m_1in [0.003,0.010]$ eV and the Dirac CP violating phase $delta_{rm CP}in[256.72^circ,283.33^circ]$.