12,328 research outputs found
Inconsistencies in Interpreting the Atmospheric Neutrino Anomaly
We note a discrepancy between the value of R expected on the basis of the
muon neutrino angular distribution and the value actually observed. The energy
independence of leads to a fine tuning problem. This may be indicative of
some unaccounted for new physics.Comment: 3 pages, 5 figure
Analytic Calculation of Neutrino Mass Eigenvalues
Implicaion of the neutrino oscillation search for the neutrino mass square
difference and mixing are discussed. We have considered the effective majorana
mass m_{ee}, related for \beta\beta_{0\nu}decay. We find limits for neutrino
mass eigen value m_{i} in the different neutrino mass spectrum,which explain
the different neutrino data.Comment: 10 page
Results from K2K and status of T2K
Results from the K2K experiment and status of the T2K experiment are
reported.Comment: 9 pages, 6 figures. Talk at International Conference on New Trends in
High-Energy Physics (Crimea2005), Yalta, Ukraine, September 10-17, 200
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
Neutrino masses and mixing angles from leptoquark interactions
In this paper we show that the mixing between leptoquarks (LQ's) from
different multiplets can generate a non-trivial Majorana mass matrix
for neutrinos through one loop self energy diagrams. Such mixing can arise from
gauge invariant and renormalizable LQ-Higgs interaction terms after EW symmetry
breaking. We use the experimental indication on neutrino oscillation to find
constraints on specific combinations of LQ couplings to quark-lepton pairs and
to the SM higgs boson. These constraints are compared with the ones from
.Comment: The expressions for majorana mass matrix of neutrinos have been
corrected so that they are symmetric. Final version to be published in
Physical Review
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
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
The MSW Effect in Quantum Field Theory
We show in detail the general relationship between the Schr\"{o}dinger
equation approach to calculating the MSW effect and the quantum field
theoretical S-matrix approach. We show the precise form a generic neutrino
propagator must have to allow a physically meaningful ``oscillation
probability'' to be decoupled from neutrino production fluxes and detection
cross-sections, and explicitly list the conditions---not realized in cases of
current experimental interest---in which the field theory approach would be
useful.Comment: 20 page REVTeX file, submitted to Phys. Rev.
Neutrinos and Gauge Unification
The approximate unification of gauge couplings is the best indirect evidence
for low-energy supersymmetry, although it is not perfect in its simplest
realizations. Given the experimental evidence for small non-zero neutrino
masses, it is plausible to extend the MSSM with three right-handed neutrino
chiral multiplets, with large Majorana masses below the unification scale, so
that a see-saw mechanism can be implemented. In this extended MSSM, the
unification prediction for the strong gauge coupling constant at M_Z can be
lowered by up to \sim 5%, bringing it closer to the experimental value at
1\sigma, therefore improving significantly the accuracy of gauge coupling
unification.Comment: 5 pages, LaTeX, 1 figur
Leptogenesis with Almost Degenerate Majorana Neutrinos
We investigate the leptogenesis with almost degenerate neutrinos, in the
framework of democratic mass matrix, which naturally explains the large mixing
angles for neutrino oscillations as well as quark masses and mixing matrix. We
find that the baryon asymmetry in the present universe is explained via the
decays of right-handed neutrinos produced nonthermally by the inflaton decay.
The model predicts neutrinoless double beta decays accessible in near future
experiments.Comment: 17 pages, LaTeX, 2 figure
- …