410 research outputs found
Neutrinoless Double Beta Decay Constraints
A brief overview is given of theoretical analyses with neutrinoless double
beta decay experiments. Theoretical bounds on the ``observable'', _betabeta,
are presented. By using experimental bounds on _betabeta, allowed regions
are obtained on the m_l-cos{2theta_12} plane, where m_l stands for the lightest
neutrino mass. It is shown that Majorana neutrinos can be excluded by combining
possible results of future neutrinoless double beta decay and {}^3H beta decay
experiments. A possibility to constrain one of two Majorana phases is discussed
also.Comment: 8 pages, 6 figures, ws-procs9x6.cls. Invited talk at 4th Workshop on
Neutrino Oscillations and their Origin (NOON2003), Kanazawa, Japan, 10-14 Feb
200
Exploring Leptonic CP Violation with Combined Analysis of Reactor and Neutrino Superbeam Experiments
We investigate the possibility to find the leptonic CP-violation by combining
the reactor experiment with the superbeam experiment without antineutrino
superbeam. We show also how much the sensitivity on CP-violating phase delta is
affected by the fact that we have not known the sign of Delta m^2_31.Comment: 4 pages, 5 eps-files, ws-procs10x7.cls, talk at the 32nd
International Conference on High Energy Physics (ICHEP04), Aug. 16-22, 2004,
Beijing, Chin
Constraints on Neutrino Parameters by Neutrinoless Double Beta Decay Experiments
Allowed regions on the m_l - cos{2\theta_{12}} plane are extracted from
results of neutrinoless double beta decay experiments. It is shown that 0.05 eV
(0 eV) < m_l < 1.85 eV is obtained for the normal (inverted) hierarchy by using
the LMA best fit parameters and the 0\nu\beta\beta result announced late last
year, which is 0.05 eV _\beta\beta < 0.84 eV with +/- 50% uncertainty of
the nuclear matrix elements.Comment: 6 pages, 3 figures, iopart.cls. Invited talk at Beyond the Desert02,
Oulu, Finland, 2-7 June 200
Probing Models of Neutrino Masses via the Flavor Structure of the Mass Matrix
We discuss what kinds of combinations of Yukawa interactions can generate the
Majorana neutrino mass matrix. We concentrate on the flavor structure of the
neutrino mass matrix because it does not depend on details of the models except
for Yukawa interactions while determination of the overall scale of the mass
matrix requires to specify also the scalar potential and masses of new
particles. Thus, models to generate Majorana neutrino mass matrix can be
efficiently classified according to the combination of Yukawa interactions. We
first investigate the case where Yukawa interactions with only leptons are
utilized. Next, we consider the case with Yukawa interactions between leptons
and gauge singlet fermions, which have the odd parity under the unbroken Z_2
symmetry. We show that combinations of Yukawa interactions for these cases can
be classified into only three groups. Our classification would be useful for
the efficient discrimination of models via experimental tests for not each
model but just three groups of models.Comment: 14 pages, 9 eps files, references adde
Exploring Leptonic CP Violation by Reactor and Neutrino Superbeam Experiments
We point out the possibility that reactor measurement of theta_{13}, when
combined with high-statistics nu_e appearance accelerator experiments, can
detect leptonic CP violation. Our proposal is based on a careful statistical
analysis under reasonable assumptions on systematic errors, assuming 2 years
running of the neutrino mode J-PARC -> Hyper-Kamiokande experiment and a few
years running of a reactor experiment with 100 ton detectors at the
Kashiwazaki-Kariwa nuclear power plant. We show that the method can be arranged
to be insensitive to the intrinsic parameter degeneracy but is affected by the
one due to unknown sign of Delta m^2_{31}.Comment: 18 pages, 5 figures, uses revtex4 and graphicx, revised treatment of
parameter degeneracy due to unknown sign of Dm^2 and tightened CP sensitivity
by using projected chi^
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