3,380 research outputs found
Improving LMA predictions with non standard interactions
It has been known for some time that the well established LMA solution to the
observed solar neutrino deficit fails to predict a flat energy spectrum for
SuperKamiokande as opposed to what the data indicates. It also leads to a
Chlorine rate which appears to be too high as compared to the data. We
investigate the possible solution to these inconsistencies with non standard
neutrino interactions, assuming that they come as extra contributions to the
and vertices that affect both the
propagation of neutrinos through solar matter and their detection. We find
that, among the many possibilities for non standard couplings, only one of them
leads to a flat SuperKamiokande spectral rate in better agreement with the data
and predicts a Chlorine rate within 1 of the observed one, while
keeping all other predictions accurate
Improving LMA predictions with non-standard interactions: neutrino decay in solar matter?
It has been known for some time that the well established LMA solution to the
observed solar neutrino deficit fails to predict a flat energy spectrum for
SuperKamiokande as opposed to what the data indicates. It also leads to a
Chlorine rate which appears to be too high as compared to the data. We
investigate the possible solution to these inconsistencies with non standard
neutrino interactions, assuming that they come as extra contributions to the
and vertices that affect both the
propagation of neutrinos in the sun and their detection. We find that, among
the many possibilities for non standard couplings, only the diagonal imaginary
ones lead to a solution to the tension between the LMA predictions and the
data, implying neutrino instability in the solar matter. Unitarity requirements
further restrict the solution and a neutrino decay into an antineutrino and a
majoron within the sun is the one favoured. Antineutrino probability is however
too small to open the possibility of experimentally observing antineutrinos
from the sun due to NSI.Comment: 27 pages, 8 figures. Final version to be published in Physical Review
Precovery of near-Earth asteroids by a citizen-science project of the Spanish Virtual Observatory
This article describes a citizen-science project conducted by the Spanish
Virtual Observatory (SVO) to improve the orbits of near-Earth asteroids (NEAs)
using data from astronomical archives. The list of NEAs maintained at the Minor
Planet Center (MPC) is checked daily to identify new objects or changes in the
orbital parameters of already catalogued objects. Using NEODyS we compute the
position and magnitude of these objects at the observing epochs of the 938 046
images comprising the Eigth Data Release of the Sloan Digitised Sky Survey
(SDSS). If the object lies within the image boundaries and the magnitude is
brighter than the limiting magnitude, then the associated image is visually
inspected by the project's collaborators (the citizens) to confirm or discard
the presence of the NEA. If confirmed, accurate coordinates and, sometimes,
magnitudes are submitted to the MPC. Using this methodology, 3,226 registered
users have made during the first fifteen months of the project more than
167,000 measurements which have improved the orbital elements of 551 NEAs (6%
of the total number of this type of asteroids). Even more remarkable is the
fact that these results have been obtained at zero cost to telescope time as
NEAs were serendipitously observed while the survey was being carried out. This
demonstrates the enormous scientific potential hidden in astronomical archives.
The great reception of the project as well as the results obtained makes it a
valuable and reliable tool for improving the orbital parameters of near-Earth
asteroids.Comment: 9 pages, 5 figures. Accepted in Astron. Nach
Solar Neutrinos: Spin Flavour Precession and LMA
The time dependence that appears to be hinted by the data from the first 13
years of the solar neutrino Gallium experiments is viewed as resulting from a
partial conversion of active neutrinos to light sterile ones through the
resonant interaction between the magnetic moment of the neutrino and a varying
solar field. A summary of the model and its predictions are presented for the
forthcoming experiments Borexino and LENS.Comment: 6 pages, 3 figures, contribution to 12th Lomonosov Conference in
Elementary Particle Physics, Moscow, Aug 24-31 (2005
Possible trace of neutrino nonstandard interactions in the supernova
Neutrino non-standard interactions (NSI), previously introduced for the sun,
are studied in the supernova context. For normal hierarchy the probability for
electron neutrinos and antineutrinos at low energy () is
substantially increased with respect to the non-NSI case and joins its value
for inverse hierarchy which is constant with energy. Also for inverse hierarchy
the NSI and non-NSI probabilities are the same for each neutrino and
antineutrino species. These are the possible visible effects of NSI in the
supernova. The decay into antineutrinos, which has been previously shown to be
implied by dense matter, cannot be seen experimentally, owing to the smallness
of the antineutrino production probability.Comment: 5 pages, 3 eps figures. Acknowledgements include
Non-equilibrium correlations and entanglement in a semiconductor hybrid circuit-QED system
We present a theoretical study of a hybrid circuit-QED system composed of two
semiconducting charge-qubits confined in a microwave resonator. The qubits are
defined in terms of the charge states of two spatially separated double quantum
dots (DQDs) which are coupled to the same photon mode in the microwave
resonator. We analyze a transport setup where each DQD is attached to
electronic reservoirs and biased out-of-equilibrium by a large voltage, and
study how electron transport across each DQD is modified by the coupling to the
common resonator. In particular, we show that the inelastic current through
each DQD reflects an indirect qubit-qubit interaction mediated by off-resonant
photons in the microwave resonator. As a result of this interaction, both
charge qubits stay entangled in the steady (dissipative) state. Finite shot
noise cross-correlations between currents across distant DQDs are another
manifestation of this nontrivial steady-state entanglement.Comment: Final versio
Tolerance to mutations in the foot-and-mouth disease virus integrin-binding RGD region is different in cultured cells and in vivo and depends on the capsid sequence context.
Engineered RNAs carrying substitutions in the integrin receptor-binding Arg-Gly-Asp (RGD) region of foot-and-mouth disease virus (FMDV) were constructed (aa 141-147 of VP1 capsid protein) and their infectivity was assayed in cultured cells and suckling mice. The effect of these changes was studied in the capsid proteins of two FMDVs, C-S8c1, which enters cells through integrins, and 213hs(-), a derivative highly adapted to cell culture whose ability to infect cells using the glycosaminoglycan heparan sulfate (HS) as receptor, acquired by multiple passage on BHK-21 cells, has been abolished. The capsid sequence context determined infectivity in cultured cells and directed the selection of additional replacements in structural proteins. Interestingly, a viral population derived from a C-S8c1/L144A mutant, carrying only three substitutions in the capsid, was able to expand tropism to wild-type (wt) and mutant (mt)glycosaminoglycan-deficient CHO cells. In contrast, the 213hs(-) capsid tolerated all substitutions analysed with no additional mutations, and the viruses recovered maintained the ability of the 213hs(-) parental virus to infect wt and mt CHO cells. Viruses derived from C-S8c1 with atypical RGD regions were virulent and transmissible for mice with no other changes in the capsid. Substitution of Asp143 for Ala in the C-S8c1 capsid eliminated infectivity in cultured cells and mice. Co-inoculation with a neutralizing monoclonal antibody directed against the type C FMDV RGD region abolished infectivity of C-S8c1 virus on suckling mice, suggesting that FMDV can infect mice using integrins. Sequence requirements imposed for viral entry in vitro and in vivo are discussed
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