11 research outputs found
Sensitivity to the KARMEN Timing Anomaly at MiniBooNE
We present sensitivities for the MiniBooNE experiment to a rare exotic pion
decay producing a massive particle, Q^0. This type of decay represents one
possible explanation for the timing anomaly reported by the KARMEN
collaboration. MiniBooNE will be able to explore an area of the KARMEN signal
that has not yet been investigated
Constraints on a Massive Dirac Neutrino Model
We examine constraints on a simple neutrino model in which there are three
massless and three massive Dirac neutrinos and in which the left handed
neutrinos are linear combinations of doublet and singlet neutrinos. We examine
constraints from direct decays into heavy neutrinos, indirect effects on
electroweak parameters, and flavor changing processes. We combine these
constraints to examine the allowed mass range for the heavy neutrinos of each
of the three generations.Comment: latex, 29 pages, 7 figures (not included), MIT-CTP-221
A scheme with two large extra dimensions confronted with neutrino physics
We investigate a particle physics model in a six-dimensional spacetime, where
two extra dimensions form a torus. Particles with Standard Model charges are
confined by interactions with a scalar field to four four-dimensional branes,
two vortices accommodating ordinary type fermions and two antivortices
accommodating mirror fermions. We investigate the phenomenological implications
of this multibrane structure by confronting the model with neutrino physics
data.Comment: LATEX, 24 pages, 9 figures, minor changes in the tex
Search for a 33.9 MeV/c^2 Neutral Particle in Pion Decay
The E815 (NuTeV) neutrino experiment has performed a search for a 33.9
MeV/c^2 weakly-interacting neutral particle produced in pion decay. Such a
particle may be responsible for an anomaly in the timing distribution of
neutrino interactions in the KARMEN experiment. E815 has searched for this
particle's decays in an instrumented decay region; no evidence for this
particle was found. The search is sensitive to pion branching ratios as low as
10^-13.Comment: 4 pages; 5 figure
Primordial Nucleosynthesis with a Decaying Tau Neutrino
A comprehensive study of the effect of an unstable tau neutrino on primordial
nucleosynthesis is presented. The standard code for nucleosynthesis is modified
to allow for a massive decaying tau neutrino whose daughter products include
neutrinos, photons, pairs, and/or noninteracting (sterile) daughter
products. Tau-neutrino decays influence primordial nucleosynthesis in three
distinct ways: (i) the energy density of the decaying tau neutrino and its
daughter products affect the expansion rate tending to increase He, D, and
He production; (ii) electromagnetic (EM) decay products heat the EM plasma
and dilute the baryon-to-photon ratio tending to decrease He production and
increase D and He production; and (iii) electron neutrinos and
antineutrinos produced by tau-neutrino decays increase the weak rates that
govern the neutron-to-proton ratio, leading to decreased He production for
short lifetimes (\la 30\sec) and masses less than about 10\MeV and
increased He production for long lifetimes or large masses. The precise
effect of a decaying tau neutrino on the yields of primordial nucleosynthesis
and the mass-lifetime limits that follow depend crucially upon decay mode. We
identify four generic decay modes that serve to bracket the wider range of
possibilities:Comment: 27 pages, Latex, 12 Figures avaiable on request, FNAL--Pub--93/236-
New limits on generation mixing for massive neutrinos from pi rarr e nu decay
Improved upper limits of generation-mixing amplitudes /b U//sub ie/ are presented for the electron-flavour in the heavy neutrino mass range of 20-70 MeV//b c//sup 2/. In conjunction with astrophysical considerations the new limits tend to exclude together the existence of heavy neutrinos in the investigated mass range.Anglai