100 research outputs found
Laboratory Constraints on a 33.9 MeV/c^2 Isosinglet Neutrino: Status and Perspectives
An anomaly in the time behaviour of the signals observed by the KARMEN
Collaboration may be interpreted as the possible decay signature of a 33.9
MeV/c mainly sterile neutrino. This note discusses the parameter space
still open for the mixing of this hypothetical particle with the neutrinos of
known leptonic flavour, considering the experimental results which became
available recently, as well as those to be expected from forthcoming
measurements. It is concluded that if no positive signature is observed, the
envisaged laboratory experiments are not expected to close enterily the
parameter space of mixing amplitudes. However, a proper reassessment of the
ALEPH upper bound on the neutrino mass including the possibility of
flavour mixing, would certainly help in reducing the parameter space
left open.Comment: LaTeX file, 11 pages, one figure available on reques
Constraints on the left-right symmetric models from the unitarity of the Kobayashi-Maskawa matrix
The author surveys the experimental information which, combined with the unitarity-requirement of the Kobayashi-Maskawa matrix, provides further constraints on the parameters of the manifest left-right symmetric model. The author finds that these considerations, independently of any other input, constrain the left-right mixing angle of the two /b W/-bosons of the model to a few milliradians.Anglai
Corrélation Béta-Gamma polarise circulaire dans Au198 et Sb122.
Docteur en Sciences -- UC
Scalar interaction limits from the beta-ne correlation of trapped radioactive atoms
We have set limits on contributions of scalar interactions to nuclear beta
decay. A magneto-optical trap (MOT) provides a localized source of atoms
suspended in space, so the low-energy recoiling nuclei can freely escape and be
detected in coincidence with the beta. This allows reconstruction of the
neutrino momentum, and the measurement of the beta-neutrino correlation, in a
more direct fashion than previously possible. The beta-neutrino correlation
parameter of the 0+ to 0+ pure Fermi decay of 38mK is
=0.9981+-0.0030+-0.0037, consistent with the standard model
prediction a=1.
Comment: 4 pages, 3 figures, accepted by Phys. Rev. Lett., centroid change
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