8,684 research outputs found
Rare top quark decays in extended models
Flavor changing neutral currents (FCNC) decays t to H + c, t to Z + c, and H
to t + bar{c} are discussed in the context of Alternative Left-Right symmetric
Models (ALRM) with extra isosinglet heavy fermions where FCNC decays may take
place at tree-level and are only suppressed by the mixing between ordinary top
and charm quarks, which is poorly constraint by current experimental values.
The non-manifest case is also briefly discussed.Comment: Contributed talk given at the 10th Mexican Workhop on Particles and
Fields, Morelia, Michoacan, Mexico, 7-12 Nov 200
Sterile neutrinos, dark matter, and resonant effects in ultra high energy regimes
Interest in light dark matter candidates has recently increased in the
literature; some of these works consider the role of additional neutrinos,
either active or sterile. Furthermore, extragalactic neutrinos have been
detected with energies higher than have ever been reported before. This opens a
new window of opportunities to the study of neutrino properties that were
unreachable up to now. We investigate how an interaction potential between
neutrinos and dark matter might induce a resonant enhancement in the
oscillation probability, an effect that may be tested with future neutrino
data.Comment: 11 pages, 2 figures, to be published in PL
Improved limit on electron neutrino charge radius through a new evaluation of the weak mixing angle
We have obtained a new limit on the electron neutrino effective charge radius
from a new evaluation of the weak mixing angle by a combined fit of all
electron-(anti)neutrino electron elastic scattering measurements. Weak mixing
angle is found to be sin^2 theta_W=0.259 \pm 0.025 in the low energy regime
below 100 MeV. The electron neutrino charge radius squared is bounded to be in
the range -0.13 10^-32 cm^2 < r^2 < 3.32 10^-32 cm^2 at 90 % C.L. Both results
improve previously published analyses. We also discuss perspectives of future
experiments to improve these constraints.Comment: 10 pages, 2 figures. Final published versio
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