Bi-maximal Neutrino Mixing Pattern Reexamined

We propose a new mixing pattern for neutrinos with a nonzero mixing angle $\theta_{13}$. Under a simple form, it agrees well with current neutrino oscillation data and displays a number of intriguing features including the $\mu$-$\tau$ interchange symmetry $|U_{\mu i}|=|U_{\tau i}|$, $(i=1,2,3)$, the trimaximal mixing $|U_{\e 2}|=|U_{\mu 2}|=|U_{\tau 2}|=1/\sqrt{3}$, the self-complementarity relation $\theta_1+\theta_3=45\deg$, together with the maximal Dirac CP violation as ...

We exam the pairs of neutrino mixing matrix and suggest pairs that can be used in the construction of new mixing patterns, with "pair" denoting the equality of the modulus of a pair of matrix elements. The results show that the tri-maximal mixing in $\nu_2$ and the $\mu$-$\tau$ interchange symmetry are good choices under current experimental results. The two cases of bi-pair mixing pattern depend on the mass hierarchy of neutrinos. We also derive constraints on the CP-phase b...

Atmospheric neutrinos at low energies, $E \lsim 500$ MeV, is known to be a rich source of information of lepton mixing parameters. We formulate a simple perturbative framework to elucidate the characteristic features of neutrino oscillation at around the solar-scale enhancement due to the matter effect. The clearest message we could extract from our perturbation theory is that CP violation in the appearance oscillation probability is large, a factor of $\sim 10$ times larger ...

We point out two simple but instructive possibilities to construct the charged lepton and neutrino mass matrices, from which the nearly bi-maximal neutrino mixing with large T violation can naturally emerge. The two lepton mixing scenarios are compatible very well with current experimental data on solar and atmospheric neutrino oscillations, and one of them may lead to an observable T-violating asymmetry between \nu_\mu --> \nu_e and \nu_e --> \nu_\mu transitions in the long-...

I review the status of neutrino masses and mixings in the light of the solar and atmospheric neutrino data in the framework of two--, three-- and four neutrino mixing.

We consider corrections to vanishing U_{e3} and maximal atmospheric neutrino mixing originating from the relation U = U_ell^dagger U_nu, where U is the PMNS mixing matrix and U_ell (U_nu) is associated with the diagonalization of the charged lepton (neutrino) mass matrix. We assume that in the limit of U_ell or U_nu being the unit matrix, one has U_{e3} = 0 and theta_{23} = pi/4, while the solar neutrino mixing angle is a free parameter. Well-known special cases of the indica...

Recent measurements of the neutrino mixing angles cast doubt on the validity of the so-far popular tri-bimaximal mixing ansatz. We propose a parametrization for the neutrino mixing matrix where the reactor angle seeds the large solar and atmospheric mixing angles, equal to each other in first approximation. We suggest such bi-large mixing pattern as a model building standard, realized when the leading order value of the reactor angle equals the Cabibbo angle.

We give a phenomenological interpretation of atmospheric and solar neutrino oscillations by considering two scenarios for the neutrino mass spectrum: (a) m_1 \ll m_2 \ll m_3 and (b) m_1 \approx m_2 \approx m_3. A new parametrization of the flavor mixing matrix, which can naturally reflect the hierarchy of lepton masses in scenario (a) and the approximate decoupling of solar and atmospheric neutrino oscillations, is highlighted. For scenario (b) an ansatz starting with flavor ...

We show that the bimaximal neutrino mixing pattern suggested by the solar and atmospheric neutrino data can be derived from the maximal, symmetric, four neutrino mixing in the limit that one of the neutrinos is made heavy. Imposing the constraints of no neutrinoless double beta decay and a 20% hot dark matter component of the universe leads to a three neutrino mass matrix recently suggested by Georgi and Glashow. Our result can be useful in constructing theoretical models for...

We propose a scheme of lepton mixing in which the unitary matrix that diagonalizes the neutrino mass matrix is bimaximal and the deviation from bimaximal of the lepton mixing matrix is due to the unitary matrix that diagonalizes the charged-lepton mass matrix. This matrix is assumed to be hierarchical, like the quark mixing matrix. It is shown that in general it is possible to have a sizable value for |U_{e3}| together with an effective two-neutrino maximal mixing in solar ne...