1,072 research outputs found
Neutrino Decay and Atmospheric Neutrinos
We reconsider neutrino decay as an explanation for atmospheric neutrino
observations. We show that if the mass-difference relevant to the two mixed
states \nu_\mu and \nu_\tau is very small (< 10^{-4} eV^2), then a very good
fit to the observations can be obtained with decay of a component of \nu_\mu to
a sterile neutrino and a Majoron. We discuss how the K2K and MINOS
long-baseline experiments can distinguish the decay and oscillation scenarios.Comment: 9 pages, Revtex, uses epsf.sty, 3 postscript figures. Additions and
corrections to references, minor changes in the text and to some number
SPORADIC PARKINSON DISEASE AND AMYOTROPHIC LATERAL SCLEROSIS COMPLEX (BRAIT-FAHN-SCHWARTZ DISEASE).
The Energy and Zenith Angle Distribution of Upward Going Muons and Neutrino Oscillations
The energy and zenith angle distribution of neutrino induced, upward going
muons can give direct information on the presence of --oscillations in
precisely the range of parameters suggested as a solution of the atmospheric
neutrino problem. We discuss here the uncertainties in the theoretical
prediction. The shape of the zenith angle distribution of the muon flux is
quite insensitive to modifications of the theoretical input and is a good probe
for the existence of neutrino oscillations. We conclude that the existing data
sample on --induced muons has the statistical power to confirm or refute
the --oscillation solution of the atmospheric neutrino problem.Comment: 8 pages Latex, with 3 embedded eps figure
Comparison of 3-Dimensional and 1-Dimensional Schemes in the calculation of Atmospheric Neutrinos
A 3-dimensional calculation of atmospheric neutrinos flux is presented, and
the results are compared with those of a 1-dimensional one. In this study,
interaction and propagation of particles is treated in a 3-dimensional way
including the curvature of charged particles due to the geomagnetic field,
which is assumed to be a dipole field. The purpose of this paper is limited to
the comparison of calculation schemes. The updated flux value with new
interaction model and primary flux model will be reported in a separate paper.
Except for nearly horizontal directions, the flux is very similar to the
result of 1 dimensional calculations. However, for near-horizontal directions
an enhancement of the neutrino flux is seen even at energies as high as 1 GeV.
The production height of neutrinos is lower than the prediction by
1-dimensional calculation for near-horizontal directions, and is a little
higher for near-vertical directions. However, the difference is not evident
except for near-horizontal directions.Comment: 22 pages, 15figure
Suppressed star formation in circumnuclear regions in Seyfert galaxies
Feedback from black hole activity is widely believed to play a key role in
regulating star formation and black hole growth. A long-standing issue is the
relation between the star formation and fueling the supermassive black holes in
active galactic nuclei (AGNs). We compile a sample of 57 Seyfert galaxies to
tackle this issue. We estimate the surface densities of gas and star formation
rates in circumnuclear regions (CNRs). Comparing with the well-known
Kennicutt-Schmidt (K-S) law, we find that the star formation rates in CNRs of
most Seyfert galaxies are suppressed in this sample. Feedback is suggested to
explain the suppressed star formation rates.Comment: 1 color figure and 1 table. ApJ Letters in pres
Breaking Eight-fold Degeneracies in Neutrino CP Violation, Mixing, and Mass Hierarchy
We identify three independent two-fold parameter degeneracies (\delta,
\theta_{13}), sgn(\delta m^2_{31}) and (\theta_{23}, \pi/2-\theta_{23})
inherent in the usual three-neutrino analysis of long-baseline neutrino
experiments, which can lead to as much as an eight-fold degeneracy in the
determination of the oscillation parameters. We discuss the implications these
degeneracies have for detecting CP violation and present criteria for breaking
them. A superbeam facility with a baseline at least as long as the distance
between Fermilab and Homestake (1290 km) and a narrow band beam with energy
tuned so that the measurements are performed at the first oscillation peak can
resolve all the ambiguities other than the (\theta_{23}, \pi/2-\theta_{23})
ambiguity (which can be resolved at a neutrino factory) and a residual (\delta,
\pi-\delta) ambiguity. However, whether or not CP violation occurs in the
neutrino sector can be ascertained independently of the latter two ambiguities.
The (\delta,\pi-\delta) ambiguity can be eliminated by performing a second
measurement to which only the \cos\delta terms contribute. The hierarchy of
mass eigenstates can be determined at other oscillation peaks only in the most
optimistic conditions, making it necessary to use the first oscillation
maximum. We show that the degeneracies may severely compromise the ability of
the proposed SuperJHF-HyperKamiokande experiment to establish CP violation. In
our calculations we use approximate analytic expressions for oscillation
probabilitites that agree with numerical solutions with a realistic Earth
density profile.Comment: Revtex (singlespaced), 35 pages, 15 postscript figures, uses
psfig.st
Atmospheric neutrino flux from 3-dimensional simulation
The atmospheric muon and neutrino flux have been simulated using the same
approach which successfully accounted for the recent secondary proton, electron
and positron flux measurements in orbit by the AMS experiment. For the muon
flux, a good agreement is obtained with the CAPRICE and HEAT data for altitudes
ranging from sea level up to about 38 km. The general features of the
calculated atmospheric neutrino flux are reported and discussed. The flux
obtained at the Super-Kamiokande experiment location are reported and compared
with other calculations. For low neutrino energies the flux obtained is
significantly smaller than that used in the data analysis of underground
experiment. The simulation results for the SOUDAN experiment site are also
reported.Comment: 33 pages, 27 figures, 12 tables, final version for Phys. Rev.
Neutrino Factories and the "Magic" Baseline
We show that for a neutrino factory baseline of a
``clean'' measurement of becomes possible, which is
almost unaffected by parameter degeneracies. We call this baseline "magic"
baseline, because its length only depends on the matter density profile. For a
complete analysis, we demonstrate that the combination of the magic baseline
with a baseline of 3000 km is the ideal solution to perform equally well for
the , sign of , and CP violation
sensitivities. Especially, this combination can very successfully resolve
parameter degeneracies even below .Comment: Minor changes, final version to appear in PRD, 4 pages, 3 figures,
RevTe
Investigating the effects of COVID-19 lockdown on Italian children and adolescents with and without neurodevelopmental disorders: a cross-sectional study
We conducted a cross-sectional study to compare the impact of social distancing and lifestyle changes that occurred during Corona Virus Disease 2019 (COVID-19) lockdown on children and adolescents with and without Neurodevelopmental Disorders (NDDs). An online questionnaire was administered in order to investigate the effects of NDD condition, socio-demographic status, familiar/home environment and COVID-19 exposure on their lives during a two months period of social isolation. We used logistic regression, focusing on five endpoints (remote learning, lifestyle, stress/anxiety, sociality, scolding) to define the extent of these effects. Most questions were paired up to parents and children, to verify the occurrence of agreement. 8305 questionnaires were analyzed, 1362 of which completed by NDDs and 6943 by controls. Results showed that the presence of a NDD, compared to controls, had a significant impact on: Remote Learning (i.e. subjects with NDDs experienced more difficulties in attending online classes and studying), Sociality (i.e. subjects with NDDs missed their schoolmates less), Scolding (i.e. subjects with NDDs were scolded more often) and Anxiety (i.e. subjects with NDDs were perceived by their parents as more anxious). Substantial agreement between parents and children arose from questions concerning Remote learning, Lifestyle and Scolding. The current study actually points out that having a NDD gives account for a stronger influence on school performance and on behavioral and psychological aspects, during a two months lockdown. Such results may provide useful information to governments and school authorities on how carrying through supportive strategies for youth affected by NDDs
Neutrino suppression and extra dimensions: a minimal model
We study flavour neutrinos confined to our 4-dimensional world coupled to one
"bulk" state, i.e. a Kaluza-Klein tower. We discuss the spatial development of
the neutrino disappearance, the possibility of resurgence and the effective
flavour transitions induced in this mechanism. We show that even a simple model
can produce an energy-independent suppression at large distances, and relate
this to experimental data.Comment: 14 pages, 8 figures; the exclusion of sterile neutrinos by
SuperKamiokande is discussed; references adde
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