551 research outputs found

### Violation of Equivalence Principle and Solar Neutrinos

We have updated the analysis for the solution to the solar neutrino problem
by the long-wavelength neutrino oscillations induced by a tiny breakdown of the
weak equivalence principle of general relativity, and obtained a very good fit
to all the solar neutrino data.Comment: 3 pages, 5 figures, uses espcrc2.sty, Talk presented by H. Nunokawa
at Europhysics Neutrino Oscillation Workshop (NOW2000), Otranto, Italy,
September 9-16, 200

### The Solar Neutrino Problem in the Light of a Violation of the Equivalence Principle

We have found that long-wavelength neutrino oscillations induced by a tiny
breakdown of the weak equivalence principle of general relativity can provide a
viable solution to the solar neutrino problem.Comment: 3 pages, 1 eps figure, Talk given by R. Zukanovich Funchal at the
VIth International Workshop on ``Topics in Astroparticle and Underground
Physics'' (TAUP99), Sep. 6-10, 1999, College de France, Paris - Franc

### High intensity tapping regime in a frustrated lattice gas model of granular compaction

In the frame of a well established lattice gas model for granular compaction,
we investigate the high intensity tapping regime where a pile expands
significantly during external excitation. We find that this model shows the
same general trends as more sophisticated models based on molecular dynamic
type simulations. In particular, a minimum in packing fraction as a function of
tapping strength is observed in the reversible branch of an annealed tapping
protocol.Comment: 5 pages, 4 figure

### General bounds on non-standard neutrino interactions

We derive model-independent bounds on production and detection non-standard
neutrino interactions (NSI). We find that the constraints for NSI parameters
are around O(10^{-2}) to O(10^{-1}). Furthermore, we review and update the
constraints on matter NSI. We conclude that the bounds on production and
detection NSI are generally one order of magnitude stronger than their matter
counterparts.Comment: 18 pages, revtex4, 1 axodraw figure. Minor changes, matches published
versio

### Status of atmospheric neutrino(mu)<-->neutrino(tau) oscillations and decoherence after the first K2K spectral data

We review the status of nu_mu-->nu_tau flavor transitions of atmospheric
neutrinos in the 92 kton-year data sample collected in the first phase of the
Super-Kamiokande (SK) experiment, in combination with the recent spectral data
from the KEK-to-Kamioka (K2K) accelerator experiment (including 29 single-ring
muon events). We consider a theoretical framework which embeds flavor
oscillations plus hypothetical decoherence effects, and where both standard
oscillations and pure decoherence represent limiting cases. It is found that
standard oscillations provide the best description of the SK+K2K data, and that
the associated mass-mixing parameters are determined at 1 sigma (and d.o.f.=1)
as: Delta m^2=(2.6 +- 0.4)x10^{-3} eV^2 and sin^2(2theta)=1.00+0.00-0.05. As
compared with standard oscillations, the case of pure decoherence is
disfavored, although it cannot be ruled out yet. In the general case,
additional decoherence effects in the nu_mu-->nu_tau channel do not improve the
fit to the SK and K2K data, and upper bounds can be placed on the associated
decoherence parameter. Such indications, presently dominated by SK, could be
strengthened by further K2K data, provided that the current spectral features
are confirmed with higher statistics. A detailed description of the statistical
analysis of SK and K2K data is also given, using the so-called ``pull''
approach to systematic uncertainties.Comment: 18 pages (RevTeX) + 12 figures (PostScript

### Seesaw tau lepton mass and calculable neutrino masses in a 3-3-1 model

In a version of the 3-3-1 model proposed by Duong and Ma the introduction of
the scalar sextet for giving mass to the charged leptons is avoided by adding a
singlet charged lepton. We show that in this case the $\tau$ lepton gains mass
through a seesaw--like mechanism. Besides we show how to generate neutrino
masses at the tree and at the 1-loop level with the respective
Maki-Nakagawa-Sakata leptonic mixing matrices.Comment: revtex, 5 pages and one eps figure. Published versio

### Damping signatures in future neutrino oscillation experiments

We discuss the phenomenology of damping signatures in the neutrino
oscillation probabilities, where either the oscillating terms or the
probabilities can be damped. This approach is a possibility for tests of
non-oscillation effects in future neutrino oscillation experiments, where we
mainly focus on reactor and long-baseline experiments. We extensively motivate
different damping signatures due to small corrections by neutrino decoherence,
neutrino decay, oscillations into sterile neutrinos, or other mechanisms, and
classify these signatures according to their energy (spectral) dependencies. We
demonstrate, at the example of short baseline reactor experiments, that damping
can severely alter the interpretation of results, e.g., it could fake a value
of $\sin(2\theta_{13})$ smaller than the one provided by Nature. In addition,
we demonstrate how a neutrino factory could constrain different damping models
with emphasis on how these different models could be distinguished, i.e., how
easily the actual non-oscillation effects could be identified. We find that the
damping models cluster in different categories, which can be much better
distinguished from each other than models within the same cluster.Comment: 33 pages, 5 figures, LaTeX. Final version published in JHE

### IceCube expectations for two high-energy neutrino production models at active galactic nuclei

We have determined the currently allowed regions of the parameter spaces of
two representative models of diffuse neutrino flux from active galactic nuclei
(AGN): one by Koers & Tinyakov (KT) and another by Becker & Biermann (BB). Our
observable has been the number of upgoing muon-neutrinos expected in the
86-string IceCube detector, after 5 years of exposure, in the range 10^5 <
E/GeV < 10^8. We have used the latest estimated discovery potential of the
IceCube-86 array at the 5-sigma level to determine the lower boundary of the
regions, while for the upper boundary we have used either the AMANDA upper
bound on the neutrino flux or the more recent preliminary upper bound given by
the half-completed IceCube-40 array (IC40). We have varied the spectral index
of the proposed power-law fluxes, alpha, and two parameters of the BB model:
the ratio between the boost factors of neutrinos and cosmic rays,
Gamma_nu/Gamma_{CR}, and the maximum redshift of the sources that contribute to
the cosmic-ray flux, zCRmax. For the KT model, we have considered two
scenarios: one in which the number density of AGN does not evolve with redshift
and another in which it evolves strongly, following the star formation rate.
Using the IC40 upper bound, we have found that the models are visible in
IceCube-86 only inside very thin strips of parameter space and that both of
them are discarded at the preferred value of alpha = 2.7 obtained from fits to
cosmic-ray data. Lower values of alpha, notably the values 2.0 and 2.3 proposed
in the literature, fare better. In addition, we have analysed the capacity of
IceCube-86 to discriminate between the models within the small regions of
parameter space where both of them give testable predictions. Within these
regions, discrimination at the 5-sigma level or more is guaranteed.Comment: 24 pages, 6 figures, v2: new IceCube-40 astrophysical neutrino upper
bound and IceCube-86 discovery potential used, explanation of AGN flux models
improved, only upgoing neutrinos used, conclusions strengthened. Accepted for
publication in JCA

### Experimental feasibility of measuring the gravitational redshift of light using dispersion in optical fibers

This paper describes a new class of experiments that use dispersion in
optical fibers to convert the gravitational frequency shift of light into a
measurable phase shift or time delay. Two conceptual models are explored. In
the first model, long counter-propagating pulses are used in a vertical fiber
optic Sagnac interferometer. The second model uses optical solitons in
vertically separated fiber optic storage rings. We discuss the feasibility of
using such an instrument to make a high precision measurement of the
gravitational frequency shift of light.Comment: 11 pages, 12 figure

### Atmospheric Neutrino Oscillations and New Physics

We study the robustness of the determination of the neutrino masses and
mixing from the analysis of atmospheric and K2K data under the presence of
different forms of phenomenologically allowed new physics in the nu_mu--nu_tau
sector. We focus on vector and tensor-like new physics interactions which allow
us to treat, in a model independent way, effects due to the violation of the
equivalence principle, violations of the Lorentz invariance both CPT conserving
and CPT violating, non-universal couplings to a torsion field and non-standard
neutrino interactions with matter. We perform a global analysis of the full
atmospheric data from SKI together with long baseline K2K data in the presence
of nu_mu -> nu_tau transitions driven by neutrino masses and mixing together
with sub-dominant effects due to these forms of new physics. We show that
within the present degree of experimental precision, the extracted values of
masses and mixing are robust under those effects and we derive the upper bounds
on the possible strength of these new interactions in the nu_mu--nu_tau sector.Comment: 22 pages, LaTeX file using RevTEX4, 5 figures and 4 tables include

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