718 research outputs found
Neutrino-nucleus interaction rates at a low-energy beta-beam facility
We compute the neutrino detection rates to be expected at a low-energy
beta-beam facility. We consider various nuclei as neutrino detectors and
compare the case of a small versus large storage ring.Comment: 6 pages, 3 figure
A Model for Neutrino Warm Dark Matter and Neutrino Oscillations
The muon- and tau-neutrinos with the mass in the keV range, which are allowed
in a low reheating temperature cosmology, can compose the warm dark matter of
the universe. A model of four light neutrinos including the keV scale
and is studied, which combines the seesaw mechanism and the Abelian
flavor symmetry. The atmospheric neutrino anomaly is due to the
oscillation. The solar neutrino problem is answered by the
oscillation into the light sterile neutrino, where the SMA, LMA, and LOW-QVO
solutions can be accommodated in our scenario.Comment: 11 pages, Final version to appear in PLB, References adde
Improved limits on nuebar emission from mu+ decay
We investigated mu+ decays at rest produced at the ISIS beam stop target.
Lepton flavor (LF) conservation has been tested by searching for \nueb via the
detection reaction p(\nueb,e+)n. No \nueb signal from LF violating mu+ decays
was identified. We extract upper limits of the branching ratio for the LF
violating decay mu+ -> e+ \nueb \nu compared to the Standard Model (SM) mu+ ->
e+ nue numub decay: BR < 0.9(1.7)x10^{-3} (90%CL) depending on the spectral
distribution of \nueb characterized by the Michel parameter rho=0.75 (0.0).
These results improve earlier limits by one order of magnitude and restrict
extensions of the SM in which \nueb emission from mu+ decay is allowed with
considerable strength. The decay \mupdeb as source for the \nueb signal
observed in the LSND experiment can be excluded.Comment: 10 pages, including 1 figure, 1 tabl
Telling three from four neutrinos at the Neutrino Factory
We upgrade the study of the physical reach of a Neutrino Factory considering
the possibility to distinguish a three (active) neutrino oscillation scenario
from the scenario in which a light sterile neutrino is also present. The
distinction is easily performed in the so--called 2+2 scheme, but also in the
more problematic 3+1 scheme it can be attained in some regions of the parameter
space. We also discuss the CP violating phase determination, showing that the
effects of a large phase in the three--neutrino theory cannot be reproduced in
a four--neutrino, CP conserving, model.Comment: 21 Latex2e pages, 9 figures using epsfig; minor changes and a
footnote added, to be published on Nucl. Phys.
Shell-model calculations of neutrino scattering from 12C
Neutrino reaction cross-sections, , ,
-capture and photoabsorption rates on C are computed within a
large-basis shell-model framework, which included excitations up to
. When ground-state correlations are included with an open
-shell the predictions of the calculations are in reasonable agreement with
most of the experimental results for these reactions. Woods-Saxon radial wave
functions are used, with their asymptotic forms matched to the experimental
separation energies for bound states, and matched to a binding energy of 0.01
MeV for unbound states. For comparison purposes, some results are given for
harmonic oscillator radial functions. Closest agreement between theory and
experiment is achieved with unrestricted shell-model configurations and
Woods-Saxon radial functions. We obtain for the neutrino-absorption inclusive
cross sections: cm for the
decay-in-flight flux in agreement with the LSND datum of
cm; and cm for the decay-at-rest flux, less than the
experimental result of cm.Comment: 19 pages. ReVTeX. No figure
Muon-anti-neutrino <---> electron-anti-neutrino mixing: analysis of recent indications and implications for neutrino oscillation phenomenology
We reanalyze the recent data from the Liquid Scintillator Neutrino Detector
(LSND) experiment, that might indicate anti-nu_muanti-nu_e mixing. This
indication is not completely excluded by the negative results of established
accelerator and reactor neutrino oscillation searches. We quantify the region
of compatibility by means of a thorough statistical analysis of all the
available data, assuming both two-flavor and three-flavor neutrino
oscillations. The implications for various theoretical scenarios and for future
oscillation searches are studied. The relaxation of the LSND constraints under
different assumptions in the statistical analysis is also investigated.Comment: 17 pages (RevTeX) + 9 figures (Postscript) included with epsfig.st
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
The silver channel at the Neutrino Factory
We notice that looking for at the same time as oscillations could significantly help to reduce the errors in the
leptonic CP-violating phase measurement. We show how the (``golden'') and (``silver'') transitions
observed at an OPERA-like 2 Kton lead-emulsion detector at L = 732 Km, in
combination with the transitions observed at a 40 Kton
magnetized iron detector with a baseline of L = 3000 Km, strongly reduce the
so-called ambiguity. We also show how a moderate
increase in the OPERA-like detector mass (4 Kton instead of 2 Kton) completely
eliminates the clone regions even for small values of .Comment: Latex2e, 36 pages, using epsfi
Microscopic theories of neutrino-^{12}C reactions
In view of the recent experiments on neutrino oscillations performed by the
LSND and KARMEN collaborations as well as of future experiments, we present new
theoretical results of the flux averaged and
cross sections. The approaches used are
charge-exchange RPA, charge-exchange RPA among quasi-particles (QRPA) and the
Shell Model. With a large-scale shell model calculation the exclusive cross
sections are in nice agreement with the experimental values for both reactions.
The inclusive cross section for coming from the decay-in-flight of
is to be compared to the experimental value
of , while the one due to
coming from the decay-at-rest of is which
agrees within experimental error bars with the measured values. The shell model
prediction for the decay-in-flight neutrino cross section is reduced compared
to the RPA one. This is mainly due to the different kind of correlations taken
into account in the calculation of the spin modes and partially due to the
shell-model configuration basis which is not large enough, as we show using
arguments based on sum-rules.Comment: 17 pages, latex, 5 figure
- âŠ