30 research outputs found
Can The Majorana neutrino CP-violating phases be restricted ?
We reanalyze the constraints in neutrino masses and MNS lepton mixing
parameters using the new data from the terrestrial (KamLAND) and astrophysical
(WMAP) observations together with the HEIDELBERG-MOSCOW double beta decay
experiment. It leads us to the almost degenerate or inverse hierarchy neutrino
mass scenario. We discuss the possibility of getting the bound for the Majorana
CP violating phase.Comment: 6 pages, 2 figure
CP Violations in Lepton Number Violation Processes and Neutrino Oscillations
We examine the constraints on the MNS lepton mixing matrix from the present
and future experimental data of the neutrino oscillation and lepton number
violation processes. We introduce a graphical representation of the CP
violation phases which appear in the lepton number violation processes such as
neutrinoless double beta decay, the conversion, and the K decay,
Using this graphical representation, we derive the
constraints on the CP violation phases in the lepton sector.Comment: 21pp, REVTeX, 9 Figure
SO(10) GUT and Quark-Lepton Mass Matrices
The phenomenological model that all quark and lepton mass matrices have the
same zero texture, namely their (1,1), (1,3) and (3,1) components are zeros, is
discussed in the context of SO(10) Grand Unified Theories (GUTs). The mass
matrices of type I for quarks are consistent with the experimental data in the
quark sector. For the lepton sector, consistent fitting to the data of neutrino
oscillation experiments force us to use the mass matrix for the charged leptons
which is slightly deviated from type I. Given quark masses and charged lepton
masses, the model includes 19 free parameters, whereas the SO(10) GUTs gives 16
constrained equations. Changing the remaining three parameters freely, we can
fit all the entries of the CKM quark mixing matrix and the MNS lepton mixing
matrix, and three neutrino masses consistently with the present experimental
data.Comment: 32pp, REV TeX, 12 EPS Figure
MNS Parameters from Neutrino Oscillations, Single Beta Decay and Double Beta Decay
We examine the constraints on the MNS lepton mixing matrix =66rom the present
and future experimental data of the neutrino oscillation, tritium beta decay,
and neutrinoless double beta decay for Majorana neutrinos. We show that the
small mixing angle solutions for solar neutrino problem are disfavored for
small averaged mass () of neutrinoless double beta decay ($\leq 0.01$
eV) in the inverse neutrino mass hierarchy scenario. This is the case even in
the normal mass hierarchy scenario except for very restrictive value of the
averaged neutrino mass ($\bar{m_\nu}$) of single beta decay. The lower mass
bound for $\bar{m_\nu}$ is given from the present neutrino oscillation data. We
obtain some relations between and . The constraints on
the Majorana CP violating phases are also given.Comment: 25pages, 10figure
Two-parameter neutrino mass matrices with two texture zeros
We reanalyse Majorana-neutrino mass matrices M_nu with two texture zeros, by
searching for viable hybrid textures in which the non-zero matrix elements of
M_nu have simple ratios. Referring to the classification scheme of Frampton,
Glashow and Marfatia, we find that the mass matrix denoted by A1 allows the
ratios (M_nu)_{mu mu} : (Mnu)_{tau tau} = 1:1 and (M_nu)_{e tau} : (Mnu)_{mu
tau} = 1:2. There are analogous ratios for texture A2. With these two hybrid
textures, one obtains, for instance, good agreement with the data if one
computes the three mixing angles in terms of the experimentally determined
mass-squared differences Delta m^2_21 and Delta m^2_31. We could not find
viable hybrid textures based on mass matrices different from those of cases A1
and A2.Comment: 10 pages, no figures, minor changes, some references adde