944 research outputs found
Solar neutrinos: the SNO salt phase results and physics of conversion
We have performed analysis of the solar neutrino data including results from
the SNO salt phase as well as the combined analysis of the solar and the
KamLAND results. The best fit values of neutrino parameters are Delta m^2 =
7.1e-5 eV^2, tan^2\theta = 0.40 with the boron flux f_B = 1.04. New SNO results
strongly disfavor maximal mixing and the h-LMA region (Delta m^2 > 1e-4 eV^2)
which is accepted now at the 3-sigma level. We find the 3-sigma upper bounds:
Delta m^2 < 1.7e-4$ eV^2 and tan^2\theta < 0.64, and the lower bound Delta m^2
> 4.8e-5 eV^2. Non-zero 13-mixing does not change these results significantly.
The present data determine quantitatively the physical picture of the solar
neutrino conversion. At high energies relevant for SNO and Super-Kamiokande the
deviation of the effective survival probability from the non-oscillatory value
is about 10 - 14%. The oscillation effect contribution to this difference about
10% and the Earth regeneration is about 3 - 4%. At low energies (E < 1 MeV) the
matter corrections to vacuum oscillation effect are below 5%. The predictions
for the forthcoming measurements are given which include the spectral
distortion and CC/NC ratio at SNO, the Day-Night asymmetry, the KamLAND
spectrum and rate.Comment: figures and some numbers corrected, discussion of coherence loss
added, number of pages slightly change
Large mixing angle solution to the solar neutrino problem and random matter density perturbations
There are reasons to believe that mechanisms exist in the solar interior
which lead to random density perturbations in the resonant region of the Large
Mixing Angle solution to the solar neutrino problem. We find that, in the
presence of these density perturbations, the best fit point in the
(sin^2(2\theta), Delta_m^2) parameter space moves to smaller values, compared
with the values obtained for the standard LMA solution. Combining solar data
with KamLAND results, we find a new compatibility region, which we call
VERY-LOW LMA, where sin^2(2\theta) ~ 0.6 and Delta_m^2~2e-5 eV^2, for random
density fluctuations of order 5% < \xi< 8%. We argue that such values of
density fluctuations are still allowed by helioseismological observations at
small scales of order 10 - 1000 km deep inside the solar core.Comment: References and discussion added, with some small numerical
corrections implemente
Effects of magnetohydrodynamics matter density fluctuations on the solar neutrino resonant spin-flavor precession
Taking into account the stringent limits from helioseismology observations on
possible matter density fluctuations described by magnetohydrodynamics theory,
we find the corresponding time variations of solar neutrino survival
probability due to the resonant spin-flavor precession phenomenon with
amplitude of order O(10%). We discuss the physics potential of high statistics
real time experiments, like as Superkamiokande, to observe the effects of such
magnetohydrodynamics fluctuations on their data. We conclude that these
observations could be thought as a test of the resonant spin-flavor precession
solution to the solar neutrino anomaly.Comment: 16 pages, 3 figure
Neutrino Decay and Solar Neutrino Seasonal Effect
We consider the possibility of solar neutrino decay as a sub-leading effect
on their propagation between production and detection. Using current
oscillation data, we set a new lower bound to the neutrino lifetime at
at
C.L.. Also, we show how seasonal variations in the solar neutrino data
can give interesting additional information about neutrino lifetime
Non-standard neutrinos interactions in a 331 model with minimum Higgs sector
We present a detailed analysis of a class of extensions to the SM Gauge
chiral symmetry (331 model), where
the neutrino electroweak interaction with matter via charged and neutral
current is modified through new gauge bosons of the model. We found the
connections between the non-standard contributions on 331 model with
non-standard interactions. Through limits of such interactions in cross section
experiments we constrained the parameters of the model, obtaining that the new
energy scale of this theory should obey TeV and the new bosons of the
model must have masses greater than 610 GeV.Comment: 17 Pages, latex, 1 Table
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