118486547
A shift from democratic to tri-bimaximal neutrino mixing with relatively large theta(13)
Recent neutrino oscillation data hint that the smallest neutrino mixing angle theta(13) is possible to lie in the range 5 degrees less than or similar to theta(13) less than or similar to 12 degrees. We show that reasonable perturbations to the democratic mixing pattern, which is geometrically related to the tri-bimaximal mixing pattern through an equal shift theta(*) similar or equal to 9.7 degrees of two large mixing angles, can naturally produce a nearly tri-bimaximal neutrino mixing matrix V with sufficiently large theta(13). Two especially simple but viable scenarios of V are proposed and their phenomenological consequences are discussed. (C) 2010 Elsevier B.V. All rights reserved.
118569125
Intrinsic Deviation from the Tri-bimaximal Neutrino Mixing in a Class of A 4 Flavor Models
It is well known that the tri-bimaximal neutrino mixing pattern V-0 can be derived from a class of flavor models with the non-Abelian A(4) symmetry. We point out that small corrections to V-0, which are inherent in the A(4) models and arise from both the charged-lepton and neutrino sectors, have been omitted in the previous works. We show that such corrections may lead the 3 x 3 neutrino mixing matrix V to a non-unitary deviation from V-0, but they cannot result in a nonzero value of theta(13) or any new CF-violating phases. Current experimental constraints on the unitarity of V allow us to constrain the model parameters to some extent. (C) 2010 Elsevier B.V. All rights reserved.
16484665
How to describe neutrino mixing and CP violation
Abstract We present a classification of possible parametrizations of the 3×3 lepton flavor mixing matrix in terms of the rotation and phase angles. A particular parametrization, which is most convenient to describe the observables of neutrino oscillations and that of the neutrinoless double beta decay, is studied in detail. The possibility to determine the Dirac- and Majorana-type CP-violating phases are also discussed.
14767884
Commutators of lepton mass matrices, CP violation, and matter effects in medium-baseline neutrino experiments
We introduce the commutators of lepton mass matrices to describe the phenomenon of lepton flavor mixing, and establish their relations to the effective Hamiltonians responsible for the propagation of neutrinos. The determinants of those commutators an invariant under matter effects, leading to an instructive relationship between the universal CP-violating parameters in vacuum and in matter. in the scenario of low-energy (100 MeV less than or equal toE less than or equal to1 GeV) and medium-baseline (100 km less than or equal toL less than or equal to 400 km) neutrino experiments, we illustrate the features of lepton flavor mixing and CP violation. The terrestrial matter effects on CP- and T-violating asymmetries in nu (e) nu (mu) and )over bar>(e) )over bar>(mu) neutrino oscillations are also discussed. We demonstrate that a relatively pure signal of leptonic CP violation at the percent level can be established from such medium-baseline experiments with low-energy neutrino beams.
17692744
Getting at the CP angles
In anticipation for intensive experimental effort on B physics, theorists have introduced many ingenious ways to measure properties of the unitarity triangle. We review some of these methods. We will be critical in the hope that, if there is any defect in them, it can be remedied either theoretically or experimentally.
1975103
Vanishing effective mass of neutrinoless double beta decay
We stress the point that massive neutrinos may be Majorana particles even if the effective mass of the neutrinoless double beta decay (ee) vanishes. We show that current neutrino oscillation data do allow (ee)=0 to hold, if the Majorana CP-violating phases lie in two specific regions. Strong constraints on the neutrino mass spectrum can then be obtained. A possible texture of the neutrino mass matrix is also illustrated under the (ee)=0 condition.
121307979
Triaxiality of the yrast states of odd-A Lu isotopes
The energy spectra and electromagnetic transition probabilities of the negative-parity yrast states in odd-A Lu isotopes (Z=71) are investigated systematically using the particle-rotor model and are compared with experimental data before and after the band crossing. It is noted that the moment of inertia of the core after the band crossing is as much a smooth function of the total angular momentum I, as that before the band crossing and can be described by the ab formula. Appreciably different are the triaxial deformations before (similar to 20 degrees) and after (similar to+10 degrees) the band crossing for Lu-161,Lu-163,Lu-165, while they are more or less similar (similar to-10 degrees) for Lu-167 determined from the calculation. [S0556-2813(99)03910-2].