88 research outputs found
The Majorana Neutrino Mass Matrix with One Texture Zero and One Vanishing Eigenvalue
Possible patterns of the Majorana neutrino mass matrix with one texture
zero and one vanishing eigenvalue are classified and discussed. We find that
three one-zero textures of with and four one-zero textures of
with are compatible with current neutrino oscillation data. The
implications of these phenomenological anstze on the neutrino mass
spectrum and the neutrinoless double beta decay are also explored in some
detail.Comment: RevTex 10 pages (with 2 PS figues). More discussions and references
adde
Rephasing Invariants of CP and T Violation in the Four-Neutrino Mixing Models
We calculate the rephasing invariants of CP and T violation in a favorable
parametrization of the 4x4 lepton flavor mixing matrix. Their relations with
the CP- and T-violating asymmetries in neutrino oscillations are derived, and
the matter effects are briefly discussed.Comment: RevTex 9 pages. Slight changes. Phys. Rev. D (in press
Distinguishable RGE running effects between Dirac neutrinos and Majorana neutrinos with vanishing Majorana CP-violating phases
In a novel parametrization of neutrino mixing and in the approximation of
-lepton dominance, we show that the one-loop renormalization-group
equations (RGEs) of Dirac neutrinos are different from those of Majorana
neutrinos even if two Majorana CP-violating phases vanish. As the latter can
keep vanishing from the electroweak scale to the typical seesaw scale, it makes
sense to distinguish between the RGE running effects of neutrino mixing
parameters in Dirac and Majorana cases. The differences are found to be quite
large in the minimal supersymmetric standard model with sizable ,
provided the masses of three neutrinos are nearly degenerate or have an
inverted hierarchy.Comment: 12 pages, 5 figure
Implications of the KamLAND Measurement on the Lepton Flavor Mixing Matrix and the Neutrino Mass Matrix
We explore some important implications of the KamLAND measurment on the
lepton flavor mixing matrix and the neutrino mass matrix . The
model-independent constraints on nine matrix elements of are obtained to a
reasonable degree of accuracy. We find that nine two-zero textures of are
compatible with current experimental data, but two of them are only marginally
allowed. Instructive predictions are given for the absolute neutrino masses,
Majorana phases of CP violation, effective masses of the tritium beta decay and
neutrinoless double beta decay.Comment: RevTex 15 pages (4 PS figures included
Vanishing Effective Mass of the Neutrinoless Double Beta Decay?
We stress that massive neutrinos may be Majorana particles even if the
effective mass of the neutrinoless double beta decay m_ee vanishes. We show
that current neutrino oscillation data do allow m_ee = 0 to hold, if the
Majorana CP-violating phases lie in two specific regions. Strong constraints on
three neutrino masses can then be obtained. We find that the neutrino mass
spectrum performs a normal hierarchy: m_1 < m_2 < m_3. A possible texture of
the neutrino mass matrix is also illustrated under the m_ee = 0 condition.Comment: RevTex 9 pages (2 PS figures included). More discussions and
references added. Results partly changed. To appear in Phys. Rev.
Measuring the Relative Strong Phase in and Decays
In a recently suggested method for measuring the weak phase in
decays, the relative strong phase in and decays (equivalently, in and \od \to K^{*+} K^-) plays a role. It is shown how a study of
the Dalitz plot in can yield information on this phase,
and the size of the data sample which would give a useful measurement is
estimated.Comment: 13 pages, latex, 5 figures, submitted to Phys. Rev. D. Appendix and
some text on additional resonant contributions adde
Radiative Corrections to Neutrino Mixing and CP Violation in the Minimal Seesaw Model with Leptogenesis
Radiative corrections to neutrino mixing and CP violation are analyzed in the
minimal seesaw model with two heavy right-handed neutrinos. We find that
textures of the effective Majorana neutrino mass matrix are essentially stable
against renormalization effects. Taking account of the
Frampton-Glashow-Yanagida ansatz for the Dirac neutrino Yukawa coupling matrix,
we calculate the running effects of light neutrino masses, lepton flavor mixing
angles and CP-violating phases for both (normal mass hierarchy) and
(inverted mass hierarchy) cases in the standard model and in its
minimal supersymmetric extension. Very instructive predictions for the
cosmological baryon number asymmetry via thermal leptogenesis are also given
with the help of low-energy neutrino mixing quantities.Comment: 21 pages, 6 figures; more references adde
Sum Rules of Neutrino Masses and CP Violation in the Four-Neutrino Mixing Scheme
We show that the commutator of lepton mass matrices is invariant under
terrestial matter effects in the four-neutrino mixing scheme. A set of
model-independent sum rules for neutrino masses, which may be generalized to
hold for an arbitrary number of neutrino families, are for the first time
uncovered. Useful sum rules for the rephasing-invariant measures of leptonic CP
violation have also been found. Finally we present a generic formula of
T-violating asymmetries and expect it to be applicable to the future
long-baseline neutrino oscillation experiments.Comment: RevTex 8 pages. 3 references added. Phys. Rev. D (in printing
Nearly Bi-Maximal Neutrino Mixing, Muon g-2 Anomaly and Lepton-Flavor-Violating Processes
We interpret the newly observed muon g-2 anomaly in the framework of a
leptonic Higgs doublet model with nearly degenerate neutrino masses and nearly
bi-maximal neutrino mixing. Useful constraints are obtained on the rates of
lepton-flavor-violating rare decays ,
and as well as the - conversion ratio .
We find that , and
depend crucially on possible non-zero but samll values of the
neutrino mixing matrix element , and they are also sensitive to the
Dirac-type CP-violating phase. In particular, we show that , and are approximately in the ratio if is much larger than , and in the
ratio if is much lower than , where and are the corresponding mass-squared
differences of atmospheric and solar neutrino oscillations.Comment: LaTex 6 pages (2 PS figures). Phys. Rev. D (in printing
Almost Maximal Lepton Mixing with Large T Violation in Neutrino Oscillations and Neutrinoless Double Beta Decay
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-baseline neutrino oscillation experiments.
Their implications on the neutrinoless double beta decay are also discussed.Comment: RevTex 15 pages (2 PS figures
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