14217283
Naturalness and Testability of TeV Seesaw Mechanisms
After outlining some popular ways to go beyond the standard model so as to generate non-zero but tiny neutrino masses, I focus On several typical seesaw mechanisms and discuss how to get a balance between their theoretical naturalness and their experimental testability. Besides possible collider signatures at the Large Hadron Collider, new and non-unitary CP-violating effects are also expected to show tip in neutrino oscillations for type-I, type-(I+II), type-III and double seesaws at the TeV scale.
14710000
Impact of fermion mass degeneracy on flavour mixing
We carry out a systematic analysis of flavour mixing and CP violation in the conceptually interesting limit where two quarks or leptons of the same charge are degenerate in mass. We pay some particular attention to the impact of neutrino mass degeneracy and Majorana phase degeneracy on the lepton flavour mixing matrix.
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.
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.
119592774
SPIN DETERMINATION AND QUANTIZED ALIGNMENT IN THE SUPERDEFORMED BANDS IN DY-152, TB-151, AND GD-150
The spin of the lowest level observed in the superdeformed band in {sup 152}Dy is determined to be {ital I}{sub 0}=25 rather than the previously assigned {ital I}{sub 0}=22. As a result, we have {ital scrI}{sup (1)}{gt}{ital scrI}{sup (2)} and both {ital scrI}{sup (1)} and {ital scrI}{sup (2)} decrease very slowly with rotational frequency. From the spin determination of the two pairs of identical bands in {sup 152}Dy and {sup 151}Tb{sup *}, {sup 151}Tb and {sup 150}Gd{sup *}, evidence has been obtained to support the assumption of quantized alignments in units of {h bar}/2.