14 research outputs found
Neutrinos Confronting Large Extra Dimensions
We study neutrino physics in a model with one large extra dimension. We
assume the existence of two four-dimensional branes in the five-dimensional
space-time, one for the ordinary particles and the other one for mirror
particles, and we investigate neutrino masses and mixings in this scheme.
Comparison of experimental neutrino data with the predictions of the model
leads to various restrictions on the parameters of the model. For instance, the
size of the extra dimension, R, turns out to be bounded from below.
Cosmological considerations seem to favor a large R. The usual mixing schemes
proposed as solutions to the solar and atmospheric neutrino anomalies are
compatible with our model.Comment: 19 pages, LATEX, 4 figure
Long Distance Contribution to and Implications for and
We estimate the long distance (LD) contribution to the magnetic part of the
transition using the Vector Meson Dominance approximation
. We find that this contribution may be significantly
larger than the short distance (SD) contribution to and could
possibly saturate the present experimental upper bound on the decay rate, eV. For the decay , which is driven by as well, we obtain an upper bound on the branching ratio from . Barring the possibility that the Quantum Chromodynamics
coefficient be much smaller than 1, also implies the approximate relation .
This relation agrees quantitatively with a recent independent estimate of the
l.h.s. by Deshpande et al., confirming that the LD contributions to are small. We find that these amount to an increase of in
the magnitude of the transition amplitude, relative to the SD
contribution alone.Comment: 16 pages, LaTeX fil
Toward precision measurements in solar neutrinos
Solar neutrino physics enters a stage of precision measurements. In this
connection we present a precise analytic description of the neutrino conversion
in the context of LMA MSW solution of the solar neutrino problem. Using the
adiabatic perturbation theory we derive an analytic formula for the
survival probability which takes into account the non-adiabatic corrections and
the regeneration effect inside the Earth. The probability is averaged over the
neutrino production region. We find that the non-adiabatic corrections are of
the order . Using the formula for the Earth regeneration
effect we discuss features of the zenith angle dependence of the flux.
In particular, we show that effects of small structures at the surface of the
Earth can be important.Comment: 26 pages, 6 figures. Version to appear in Nucl. Phys.
Sur l’auteur de «l’avant-coureur du changement du monde entier»
Ioannissian Abgar Roubenovitch. Sur l’auteur de «l’avant-coureur du changement du monde entier» . In: Annales historiques de la Révolution française, n°184, 1966. La pensée socialiste devant la Révolution française. pp. 1-14
La première ébauche du «plan» de Lange
Ioannissian Abgar Roubenovitch. La première ébauche du «plan» de Lange . In: Annales historiques de la Révolution française, n°184, 1966. La pensée socialiste devant la Révolution française. pp. 15-18