Bi-maximal Neutrino Mixing Pattern Reexamined

If, as suggested by the SuperKamiokande results, the mu neutrino and tau neutrino are maximally and ``rapidly'' mixed, this alone determines the mapping from current to mass eigenstates up to one rotation angle (theta) mixing the electron neutrino ``more slowly'', with an equal combination of the mu neutrino and tau neutrino. For sin 2 theta = 1, the resulting minimal number of free parameters, yet maximal mixing, shows agreement between extant observations of solar neutrinos...

The atmospheric neutrino oscillations and the vacuum oscillation solution of the solar neutrino problem can be consistently described by a doubly or triply degenerate neutrino spectrum as long as the high level of degeneracy required is not spoiled by radiative corrections. We show that this is the case for neutrino mass matrices generated by symmetries. This imposes a strong constraint on the mixing angles and requires the mixing should be close to bi-maximal. We briefly dis...

In drawing on an analogy with the flavor mixing observed in the quark sector we discuss a pattern of large flavor mixing angles in the lepton sector. Simple arguments based on a democratic symmetry and its violation in the lepton sector allow us to determine the flavor mixing matrix of leptons. The mixing angle relevant for solar neutrino oscillations is maximal (close to $45^{\circ}$), while the angle relevant for atmospheric neutrino oscillations is given by $\sin^2 2 \thet...

We discuss a simple predictive solution to the solar neutrino problem based on maximal vacuum neutrino oscillations. The solution can be motivated by the exact parity symmetric model which predicts that the neutrino mass eigenstates are maximal mixtures of ordinary and mirror weak eigenstates (if neutrinos are massive). We show that this proposed solution to the solar neutrino problem is in reasonable agreement with the experiments, and that in the near future this scheme may...

Radiative generation of the solar scale $\Delta_{\odot}$ is discussed in the presence of leptonic CP violation. We assume that both the solar scale and $U_{e3}$ are zero at a high scale and the weak radiative corrections generate them. It is shown that all leptonic mass matrices satisfying these requirements lead to a unique prediction $\Delta_{\odot} \cos 2\theta_{\odot}\approx 4 \delta_\tau \sin^2 \theta_A |m_{ee}|^2$ for the solar scale in terms of the radiative correction...

We have studied how observables of the neutrino mixing matrix can link up with the ones in the quark sector. The deviation from the bi-maximal flavor mixing is parameterized using a 3 x 3 unitary matrix. The neutrino mixings are investigated supposing this unitary matrix to be hierarchical like the quark mixing matrix. We obtain the remarkable prediction |U_{e3}| >= 0.03 from the experimentally allowed range tan^2 theta_{sol} = 0.24 ~ 0.89. The CP violation in neutrino oscill...

We study the phenomenological consequences of maximal and near-maximal mixing of the electron neutrino with other ($x$=tau and/or muon) neutrinos. We describe the deviations from maximal mixing in terms of a parameter $\epsilon\equiv1-2\sin^2\theta_{ex}$ and quantify the present experimental status for $|\epsilon|<0.3$. We find that the global analysis of solar neutrino data allows maximal mixing with confidence level better than 99% for $10^{-8}$ eV$^2\lsim\Delta m^2\lsim2\t...

Neutrino masses and their mixing are studied in detail in the framework of a supersymmetric standard model with bilinear R-parity violation. In this scenario, the mixing matrix among the neutrinos is in a restrictive form. We find that only the small angle MSW solution is allowed for the solar neutrino problem when the results of the CHOOZ experiment are combined with the mass squared difference and mixing angle suggested by the atmospheric neutrino data. Collider signals of ...

Three interesting scenarios for neutrino mixing, i.e., (i) small-large mixing scenario, (ii) nearly bi-maximal mixing scenario and (iii) three-flavor oscillation scenario, are analyzed in connection with three possible assignments of the maximal CP-violating phase after spontaneous symmetry breaking of SO(3) in a model with gauged SO(3) lepton flavor symmetry. As a consequence, it is found that the scenario (ii) is more reliable to be resulted in reconciling both solar and at...

We propose two schemes for the lepton mixing matrix $U = U_l^\dagger U_\nu$, where $U = U_l$ refers to the charged sector, and $U_\nu$ denotes the neutrino diagonalization matrix. We assume $U_\nu$ to be CP conserving and its three angles to be connected with the Cabibbo angle in a simple manner. CP violation arises solely from the $U_l$, assumed to have the CKM form, $U_l\simeq V_{\rm CKM}$, suggested by unification. Oscillation parameters depend on a single parameter, leadi...