15,994 research outputs found
Recent Results from the K2K (KEK-to-Kamioka) Neutrino Oscillation Experiment
The latest results of the K2K experiment are reported. The results are based
on data taken from June, 1999, to June, 2000, corresponding to a total protons on target. Twenty seven fully-contained events in the
22.5 kton fiducial volume of Super-Kamiokande (SK) are observed. The expected
number of events is estimated to be 40.3^{+4.7}_{-4.6} assuming the null
oscillations hypothesis.Comment: 7 pages, 7 figures. Talk given at the Sixth International Workshop on
Tau Lepton Physics, Victoria, BC, Canada, September 19, 200
Solar Neutrino Oscillation Parameters after KamLAND
We explore the impact of the data from the KamLAND experiment in constraining
neutrino mass and mixing angles involved in solar neutrino oscillations. In
particular we discuss the precision with which we can determine the the mass
squared difference and the mixing angle
from combined solar and KamLAND data. We show that the precision with which
\Delta m^_{solar} can be determined improves drastically with the KamLAND
data but the sensitivity of KamLAND to the mixing angle is not as good. We
study the effect of enhanced statistics in KamLAND as well as reduced
systematics in improving the precision. We also show the effect of the SNO salt
data in improving the precision. Finally we discuss how a dedicated reactor
experiment with a baseline of 70 km can improve the
sensitivity by a large amount.Comment: Talk given at 4th International Conference on Nonaccelerator New
Physics (NANP 03), Dubna, Russia, 23-28 Jun 200
Four species neutrino oscillations at -Factory: sensitivity and CP-violation
The prospects of measuring the leptonic angles and CP-odd phases at a {\em
neutrino factory} are discussed in the scenario of three active plus one
sterile neutrino. We consider the \nu_\mu \raw \nu_e LSND signal. Its
associated large mass difference leads to observable neutrino oscillations at
short ( km) baseline experiments. Sensitivities to the leptonic angles
down to can be easily achieved with a 1 Ton detector. Longer baseline
experiments ( km) with a 1 Kton detector can provide very clean tests
of CP-violation especially through tau lepton detection.Comment: 15 pages, LaTeX2e, 14 eps files, use package epsfi
Super-Kamiokande data and atmospheric neutrino decay
Neutrino decay has been proposed as a possible solution to the atmospheric
neutrino anomaly, in the light of the recent data from the Super-Kamiokande
experiment. We investigate this hypothesis by means of a quantitative analysis
of the zenith angle distributions of neutrino events in Super-Kamiokande,
including the latest (45 kTy) data. We find that the neutrino decay hypothesis
fails to reproduce the observed distributions of muons.Comment: 6 pages (RevTeX) + 2 figures (Postscript
A new parametrization of the neutrino mixing matrix for neutrino oscillations
In this paper we study three active neutrino oscillations, favored by recent
data from SuperK and SNO, using a new parametrization of the lepton mixing
matrix constructed from a linear combination of the unit matrix , and a
hermitian unitary matrix , that is, .
There are only three real parameters in including the parameter .
It is interesting to find that experimental data on atmospheric neutrino
dictates the angle to be such that the and
mixing is maximal. The solar neutrino problem is solved via the MSW
effect with a small mixing angle, with depending on one small parameter
. The resulting mixing matrix with just two parameters ( and
) predicts that the oscillating probabilities for
and to be equal and of the order . The measurement of CP asymmetries at the proposed Neutrino
Factories would also provide a test of our parametrization.Comment: 10 pages, Retex, no figure
Weak and Electromagnetic Nuclear Decay Signatures for Neutrino Reactions in SuperKamiokande
We suggest the study of events in the SuperKamiokande neutrino data due to
charged- and neutral-current neutrino reactions followed by weak and/or
electromagnetic decays of struck nuclei and fragments thereof. This study could
improve the prospects of obtaining evidence for production from oscillations and could augment the data sample used to disfavor
oscillations.Comment: 7 pages, latex, to appear in Phys. Rev. Let
Searching for Oscillations with Extragalactic Neutrinos
We propose a novel approach for studying oscillations
with extragalactic neutrinos. Active Galactic Nuclei and Gamma Ray Bursts are
believed to be sources of ultrahigh energy muon neutrinos. With distances of
100 Mpc or more, they provide an unusually long baseline for possible detection
of with mixing parameters down to
eV, many orders of magnitude below the current accelerator
experiments. By solving the coupled transport equations, we show that
high-energy 's, as they propagate through the earth, cascade down in
energy, producing the enhancement of the incoming flux in the low
energy region, in contrast to the high-energy 's, which get absorbed.
For an AGN quasar model we find the flux to be a factor of 2 to 2.5
larger than the incoming flux in the energy range between GeV and
GeV, while for a GRB fireball model, the enhancement is 10%-27% in the same
energy range and for zero nadir angle. This enhancement decreases with larger
nadir angle, thus providing a novel way to search for appearance by
measuring the angular dependence of the muons. To illustrate how the cascade
effect and the final flux depend on the steepness of the incoming
, we show the energy and angular distributions for several generic
cases of the incoming tau neutrino flux, for n=1,2 and
3.6. We show that for the incoming flux that is not too steep, the signal for
the appearance of high-energy is the enhanced production of lower
energy and their distinctive angular dependence, due to the contribution
from the decay into just below the detector.Comment: 11 pages, including 4 color figure
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