91 research outputs found
Relation between CKM and MNS Matrices Induced by Bi-Maximal Rotations in the Seesaw Mechanism
It is found that the seesaw mechanism not only explains the smallness of
neutrino masses but also accounts for the large mixing angles simultaneously,
even if the unification of the neutrino Dirac mass matrix with that of up-type
quark sector is realized. In this mechanism, we show that the mixing matrix of
the Dirac-type mass matrix gets extra rotations from the diagonalization of
Majorana mass matrix. Assuming that the mixing angles to diagonalize the
Majorana mass matrix are extremely small, we find that the large mixing angles
of leptonic sector found in atmospheric and long baseline reactor neutrino
oscillation experiments can be explained by these extra rotations. We also find
that provided the mixing angle around y-axis to diagonalize the Majorana mass
matrix vanishes, we can derive the information about the absolute values of
neutrino masses and Majorana mass responsible for the neutrinoless double beta
decay experiment through the data set of neutrino experiments. In the
simplified case that there is no CP phase, we find that the neutrino masses are
decided as and that there are no solution which
satisfy (inverted mass spectrum). Then, including all CP phases,
we reanalyze the absolute values of neutrino masses and Majorana mass
responsible for the neutrinoless double beta decay experiment.Comment: 19 pages, 7 figures, revtex4, to appear in J.PHYS.SOC.JA
Remaining inconsistencies with solar neutrinos: can spin flavour precession provide a clue?
A few inconsistencies remain after it has been ascertained that LMA is the
dominant solution to the solar neutrino problem: why is the SuperKamiokande
spectrum flat and why is the Chlorine rate prediction over two standard
deviations above the data. There also remains the ananswered and important
question of whether the active neutrino flux is constant or time varying. We
propose a scenario involving spin flavour precession to sterile neutrinos with
three active flavours that predicts a flat SuperK spectrum and a Chlorine rate
prediction more consistent with data. We also argue that running the Borexino
experiment during the next few years may provide a very important clue as to
the possible variability of the solar neutrino flux.Comment: 3 pages, 2 figures, contribution to TAUP 2009 (Rome
The effect of massive neutrinos on the matter power spectrum
We investigate the impact of massive neutrinos on the distribution of matter
in the semi-non-linear regime (0.1<k<0.6 h/Mpc). We present a suite of
large-scale N-body simulations quantifying the scale dependent suppression of
the total matter power spectrum, resulting from the free-streaming of massive
neutrinos out of high-density regions. Our simulations show a power suppression
of 3.5-90 per cent at k~0.6 h/Mpc for total neutrino mass, m_nu=0.05-1.9 eV
respectively. We also discuss the precision levels that future cosmological
datasets would have to achieve in order to distinguish the normal and inverted
neutrino mass hierarchies.Comment: 10 pages, 10 figures, 1 table, changes made to address referee repor
New Linear Codes from Matrix-Product Codes with Polynomial Units
A new construction of codes from old ones is considered, it is an extension
of the matrix-product construction. Several linear codes that improve the
parameters of the known ones are presented
Nuclear matrix elements for neutrinoless double-beta decay and double-electron capture
A new generation of neutrinoless double beta decay experiments with improved
sensitivity is currently under design and construction. They will probe
inverted hierarchy region of the neutrino mass pattern. There is also a revived
interest to the resonant neutrinoless double-electron capture, which has also a
potential to probe lepton number conservation and to investigate the neutrino
nature and mass scale. The primary concern are the nuclear matrix elements.
Clearly, the accuracy of the determination of the effective Majorana neutrino
mass from the measured 0\nu\beta\beta-decay half-life is mainly determined by
our knowledge of the nuclear matrix elements. We review recent progress
achieved in the calculation of 0\nu\beta\beta and 0\nu ECEC nuclear matrix
elements within the quasiparticle random phase approximation. A considered
self-consistent approach allow to derive the pairing, residual interactions and
the two-nucleon short-range correlations from the same modern realistic
nucleon-nucleon potentials. The effect of nuclear deformation is taken into
account. A possibility to evaluate 0\nu\beta\beta-decay matrix elements
phenomenologically is discussed.Comment: 24 pages; 80 references. arXiv admin note: substantial text overlap
with arXiv:1101.214
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