369 research outputs found
Solar mass-varying neutrino oscillations
We propose that the solar neutrino deficit may be due to oscillations of
mass-varying neutrinos (MaVaNs). This scenario elucidates solar neutrino data
beautifully while remaining comfortably compatible with atmospheric neutrino
and K2K data and with reactor antineutrino data at short and long baselines
(from CHOOZ and KamLAND). We find that the survival probability of solar MaVaNs
is independent of how the suppression of neutrino mass caused by the
acceleron-matter couplings varies with density. Measurements of MeV and lower
energy solar neutrinos will provide a rigorous test of the idea.Comment: 4 pages, 3 figures. Version to appear in PR
The effect of variation in the calorie: protein ratio of the diet on nitrogen retention and body composition in the rat
This article does not have an abstract
Confronting mass-varying neutrinos with MiniBooNE
We study the proposal that mass-varying neutrinos could provide an
explanation for the LSND signal for \bar\nu_mu to \bar\nu_e oscillations. We
first point out that all positive oscillation signals occur in matter and that
three active mass-varying neutrinos are insufficient to describe all existing
neutrino data including LSND. We then examine the possibility that a model with
four mass-varying neutrinos (three active and one sterile) can explain the LSND
effect and remain consistent with all other neutrino data. We find that such
models with a 3+1 mass structure in the neutrino sector may explain the LSND
data and a null MiniBooNE result for 0.10 < \sin^2 2\theta_x < 0.30.
Predictions of the model include a null result at Double-CHOOZ, but positive
signals for underground reactor experiments and for \nu_\mu to \nu_e
oscillations in long-baseline experiments.Comment: 22 pages, 3 figures, 1 table. Comment added about recent MINOS dat
Neutrino mass hierarchy and octant determination with atmospheric neutrinos
The recent discovery by the Daya-Bay and RENO experiments, that \theta_{13}
is nonzero and relatively large, significantly impacts existing experiments and
the planning of future facilities. In many scenarios, the nonzero value of
\theta_{13} implies that \theta_{23} is likely to be different from \pi/4.
Additionally, large detectors will be sensitive to matter effects on the
oscillations of atmospheric neutrinos, making it possible to determine the
neutrino mass hierarchy and the octant of \theta_{23}. We show that a 50 kT
magnetized liquid argon neutrino detector can ascertain the mass hierarchy with
a significance larger than 4 sigma with moderate exposure times, and the octant
at the level of 2-3 sigma with greater exposure.Comment: 4 pages, 4 figures. Version published in Phys. Rev. Let
End of the cosmic neutrino energy spectrum
There may be a high-energy cutoff of neutrino events in IceCube data. In
particular, IceCube does not observe either continuum events above 2 PeV, or
the Standard Model Glashow-resonance events expected at 6.3 PeV. There are also
no higher energy neutrino signatures in the ANITA and Auger experiments. This
absence of high-energy neutrino events motivates a fundamental restriction on
neutrino energies above a few PeV. We postulate a simple scenario to terminate
the neutrino spectrum that is Lorentz-invariance violating, but with a limiting
neutrino velocity that is always smaller than the speed of light. If the
limiting velocity of the neutrino applies also to its associated charged
lepton, then a significant consequence is that the two-body decay modes of the
charged pion are forbidden above two times the maximum neutrino energy, while
the radiative decay modes are suppressed at higher energies. Such stabilized
pions may serve as cosmic ray primaries.Comment: 6 pages. Version to appear in PL
SUSY dark matter and lepton flavor violation
We study lepton flavor-violating (LFV) processes within a supersymmetric
type-I seesaw framework with flavor-blind universal boundary conditions,
properly accounting for the effect of the neutrino sector on the dark matter
relic abundance. We consider several possibilities for the neutrino Yukawa
coupling matrix and show that in regions of SUSY parameter space that yield the
correct neutralino relic density, LFV rates can differ from naive estimates by
up to two orders of magnitude. Contrary to common belief, we find that current
LFV limits do not exclude neutrino Yukawa couplings larger than top Yukawa
couplings. We introduce the ISAJET-M program that was used for the
computations.Comment: 37 pages, 9 figures, 6 tables. Version to appear in PR
- …