1,555 research outputs found
T-violation tests for relativity principles
We consider the implications of a violation of the equivalence principle or
of Lorentz invariance in the neutrino sector for the T-asymmetry in a
three-flavour framework. We find that additional mixing due to these
mechanisms, while obeying all present bounds, can lead to a substantial
enhancement, suppression, and/or sign change in for the preferred
energies and baselines of a neutrino factory. This in turn allows for the
possibility of improving existing constraints by several orders of magnitude.Comment: 2 pages; Talk given at the 4th NuFact '02 Workshop (Neutrino
Factories Based On Muon Storage Rings), 1-6 Jul 2002, London, England; To
appear in proceeding
Lepton Polarization in Neutrino-Nucleon Interactions
We derive generic formulas for the polarization density matrix of leptons
produced in neutrino and antineutrino collisions and briefly consider some
important particular cases. Next we employ the general formalism in order to
include the final lepton mass and spin into the popular model by Rein and
Sehgal for single pion neutrinoproduction.Comment: Talk given at 10th International Workshop on High-Energy Spin Physics
(SPIN 03), Dubna, Russia, 16-20 Sep 2003. 12 pages; extended version, typos
remove
Low Earth orbit thermal control coatings exposure flight tests: A comparison of U.S. and Russian results
Both the United States (US) and Russia have conducted a variety of space environment effects on materials (SEEM) flight experiments in recent years. A prime US example was the Long Duration Exposure Facility (LDEF), which spent 5 years and 9 months in low Earth orbit (LEO) from April 1984 to January 1990. A key Russian experiment was the Removable Cassette Container experiment, (RCC-1), flown on the Mir Orbital Station from 11 January 1990 to 26 April 1991. This paper evaluates the thermal control coating materials data generated by these two missions by comparing: environmental exposure conditions, functionality and chemistry of thermal control coating materials, and pre- and post-flight analysis of absorptance, emittance, and mass loss due to atomic oxygen erosion. It will be seen that there are noticeable differences in the US and Russian space environment measurements and models, which complicates comparisons of environments. The results of both flight experiments confirm that zinc oxide and zinc oxide orthotitanate white thermal control paints in metasilicate binders (Z93, YB71, TP-co-2, TP-co-11, and TP-co-12), are the most stable upon exposure to the space environment. It is also seen that Russian flight materials experience broadens to the use of silicone and acrylic resin binders while the US relies more heavily on polyurethane
Three-particle States in Nonrelativistic Four-fermion Model
On a nonrelativistic contact four-fermion model we have shown that the simple
Lambda-cut-off prescription together with definite fine-tuning of the Lambda
dependency of "bare"quantities lead to self-adjoint semi-bounded Hamiltonian in
one-, two- and three-particle sectors. The fixed self-adjoint extension and
exact solutions in two-particle sector completely define three-particle
problem. The renormalized Faddeev equations for the bound states with Fredholm
properties are obtained and analyzed.Comment: 9 pages, LaTex, no figure
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
New Test of Supernova Electron Neutrino Emission using Sudbury Neutrino Observatory Sensitivity to the Diffuse Supernova Neutrino Background
Supernovae are rare nearby, but they are not rare in the Universe, and all
past core-collapse supernovae contributed to the Diffuse Supernova Neutrino
Background (DSNB), for which the near-term detection prospects are very good.
The Super-Kamiokande limit on the DSNB electron {\it antineutrino} flux,
cm s, is just above the
range of recent theoretical predictions based on the measured star formation
rate history. We show that the Sudbury Neutrino Observatory should be able to
test the corresponding DSNB electron {\it neutrino} flux with a sensitivity as
low as cm s,
improving the existing Mont Blanc limit by about three orders of magnitude.
While conventional supernova models predict comparable electron neutrino and
antineutrino fluxes, it is often considered that the first (and
forward-directed) SN 1987A event in the Kamiokande-II detector should be
attributed to electron-neutrino scattering with an electron, which would
require a substantially enhanced electron neutrino flux. We show that with the
required enhancements in either the burst or thermal phase fluxes, the
DSNB electron neutrino flux would generally be detectable in the Sudbury
Neutrino Observatory. A direct experimental test could then resolve one of the
enduring mysteries of SN 1987A: whether the first Kamiokande-II event reveals a
serious misunderstanding of supernova physics, or was simply an unlikely
statistical fluctuation. Thus the electron neutrino sensitivity of the Sudbury
Neutrino Observatory is an important complement to the electron antineutrino
sensitivity of Super-Kamiokande in the quest to understand the DSNB.Comment: 10 pages, 3 figure
Fluxes of atmospheric muons underwater depending on the small-x gluon density
The prompt muon contribution to the deep-sea atmospheric muon flux can serve
as a tool for probing into the small-x feature of the gluon density inside of a
nucleon, if the muon energy threshold could be lifted to 100 TeV. The prompt
muon flux underwater is calculated taking into consideration predictions of
recent charm production models in which the small-x behaviour of the gluon
distribution is probed. We discuss the possibility of distinguishing the PQCD
models of the charm production differing in the small-x exponent of the gluon
distribution, in measurements of the muon flux at energies 10-100 TeV with
neutrino telescopes.Comment: 9 pages, 4 eps figures, uses iopart.st
A Foundational View on Integration Problems
The integration of reasoning and computation services across system and
language boundaries is a challenging problem of computer science. In this
paper, we use integration for the scenario where we have two systems that we
integrate by moving problems and solutions between them. While this scenario is
often approached from an engineering perspective, we take a foundational view.
Based on the generic declarative language MMT, we develop a theoretical
framework for system integration using theories and partial theory morphisms.
Because MMT permits representations of the meta-logical foundations themselves,
this includes integration across logics. We discuss safe and unsafe integration
schemes and devise a general form of safe integration
Neutrino oscillations and uncertainty relations
We show that coherent flavor neutrino states are produced (and detected) due
to the momentum-coordinate Heisenberg uncertainty relation. The Mandelstam-Tamm
time-energy uncertainty relation requires non-stationary neutrino states for
oscillations to happen and determines the time interval (propagation length)
which is necessary for that. We compare different approaches to neutrino
oscillations which are based on different physical assumptions but lead to the
same expression for the neutrino transition probability in standard neutrino
oscillation experiments. We show that a Moessbauer neutrino experiment could
allow to distinguish different approaches and we present arguments in favor of
the 163Ho-163Dy system for such an experiment.Comment: Some small changes in section 2, results unchanged. Added referenc
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