901 research outputs found
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
New limits on neutrino magnetic moment through nonvanishing 13-mixing
FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOThe relatively large value of the neutrino mixing angle theta(13) set by recent measurements allows us to use solar neutrinos to set a limit on the neutrino magnetic moment involving the second and third flavor families, mu(23). The existence of a random magnetic field in the solar convective zone can produce a significant antineutrino flux when a nonvanishing neutrino magnetic moment is assumed. Even if we consider a vanishing neutrino magnetic moment involving the first family, electron antineutrinos are indirectly produced through the mixing between the first and third families and mu(23 )not equal 0. Using KamLAND limits on the solar flux of electron antineutrino, we set the limit mu(23) < 0.95 x 10(-1)(1)mu(B )as a reasonable assumption on the behavior of solar magnetic fields. This is the first time that a limit on mu(23) has been established in the literature directly from neutrino interactions with magnetic fields, and, interestingly enough, is comparable with the limits on the neutrino magnetic moment involving the first family and with the ones coming from modifications to the electroweak cross section.97917FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO2012/16389-12014/19164-6307269/2013-2310734/2014-2304715/2016-6304001/2017-
Eu2+ spin dynamics in the filled skutterudites EuM4Sb12 (M = Fe, Ru, Os)
We report evidence for a close relation between the thermal activation of the
rattling motion of the filler guest atoms, and inhomogeneous spin dynamics of
the Eu2+ spins. The spin dynamics is probed directly by means of Eu2+ electron
spin resonance (ESR), performed in both X-band (9.4 GHz) and Q-band (34 GHz)
frequencies in the temperature interval 4.2 < T < 300 K. A comparative study
with ESR measurements on the Beta-Eu8Ga16Ge30 clathrate compound is presented.
Our results point to a correlation between the rattling motion and the spin
dynamics which may be relevant for the general understanding of the dynamics of
cage systems.Comment: 6 pages, 4 figures, accepted for publication in Phys. Rev.
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