1,181 research outputs found
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
Seasonal Dependence in the Solar Neutrino Flux
MSW solutions of the solar neutrino problem predict a seasonal dependence of
the zenith angle distribution of the event rates, due to the non-zero latitude
at the Super-Kamiokande site. We calculate this seasonal dependence and compare
it with the expectations in the no-oscillation case as well as just-so
scenario, in the light of the latest Super-Kamiokande 708-day data. The
seasonal dependence can be sizeable in the large mixing angle MSW solution and
would be correlated with the day-night effect. This may be used to discriminate
between MSW and just-so scenarios and should be taken into account in refined
fits of the data.Comment: 4 pages, latex, RevTeX, two postscript figure
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
Quantum Dissipation in a Neutrino System Propagating in Vacuum and in Matter
Considering the neutrino state like an open quantum system, we analyze its
propagation in vacuum or in matter. After defining what can be called
decoherence and relaxation effects, we show that in general the probabilities
in vacuum and in constant matter can be written in a similar way, which is not
an obvious result in this approach. From this result, we analyze the situation
where neutrinos evolution satisfies the adiabatic limit and use this formalim
to study solar neutrinos. We show that the decoherence effect may not be
bounded by the solar neutrino data and review some results in the literature.
We discuss the current results where solar neutrinos were used to put bounds on
decoherence effects through a model-dependent approach. We conclude explaining
how and why this models are not general and we reinterpret these constraints.Comment: new version: title was changend and was added a table. To appear at
Nucl. Physic.
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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