219 research outputs found
Phenomenology of SUSY-models with spontaneously broken R-parity
We review the consequences of spontaneously broken R-parity in present and
planned lepton-lepton colliders. In the left-right models the R-parity,
, is preserved due to the gauge symmetry, but it must be
spontaneously broken in order to the scalar spectrum to be physically
consistent. The spontaneous breaking is generated via a non-vanishing VEV of at
least one of the sneutrinos, which necessarily means non-conservation of lepton
number . The R-parity violating couplings are parametrized in terms of
mixing angles, whose values depend on model parameters. Combined with the
constraints derived from low-energy measurements this yields allowed ranges for
various R-parity breaking couplings. The R-parity breaking allows for the
processes in which a single chargino or neutralino is produced, subsequently
decaying at the interaction point to non-supersymmetric particles.Comment: 6 pages, Latex, talk given in Beyond the Standard Model V in Balholm,
Norwa
Effects of degenerate sterile neutrinos on the supernova neutrino flux
We consider the possibility that there exist sterile neutrinos which are
closely degenerate in mass with the active neutrinos and mixed with them. We
investigate the effects of this kind of active-sterile neutrino mixing on the
composition of supernova neutrino flux at the Earth. If an adiabatic
MSW-transition between active and sterile neutrinos takes place, it could
dramatically diminish the electron neutrino flux.Comment: 12 pages. Final version to be published in Phys. Lett.
Testing neutrino instability with active galactic nuclei
Active galactic nuclei and gamma ray bursts at cosmological distances are
sources of high-energy electron and muon neutrinos and provide a unique test
bench for neutrino instability. The typical lifetime-to-mass ratio one can
reach there is s/eV. We study the rapid
decay channel , where is a massless or very light
scalar (possibly a Goldstone boson), and point out that one can test the
coupling strength of down to g_{ij}\lsim 10^{-8} eV/m by
measuring the relative fluxes of , and . This
is orders of magnitude more stringent bound than what one can obtain in other
phenomena, e.g. in neutrinoless double beta decay with scalar emission.Comment: 3 page
Vector boson pair production in e-e- collisions with polarized beams
The -boson pair production in collisions with polarized beams is
investigated. The helicity amplitudes are derived for general couplings and the
conditions for a good high-energy behaviour of the cross-section are given. The
results are applied to the heavy vector boson production in the context of the
left-right symmetric model. The Ward identities and the equivalence theorem are
also discussed.Comment: 17 pages+ 8 figures(uuencoded compressed ps-file appended), HU-SEFT R
1994-09 (the original version of the file was unreproducable in some
computers
Supersymmetric Left-Right Model and its Tests in Linear Colliders
We investigate phenomenological implications of a supersymmetric left-right
model based on gauge symmetry
testable in the next generation linear colliders. We concentrate in particular
on the doubly charged triplet higgsino , which we find
very suitable for experimental search. We estimate its production rate in
, , and collisions and consider its
subsequent decays. These processes have a clear discovery signature with a very
low background from other processes.Comment: 23 pages + 11 pages of figures (available on request), HU-SEFT R
1993-1
Sterile neutrino signals from supernovae
We investigate the effects of a mixing of active and sterile neutrinos on the
ratios of supernova electron neutrino flux () and antineutrino flux
() to the total flux of the other neutrino and antineutrino
flavours (). We assume that the heaviest (in the normal hierarchy)
Standard Model neutrino mixes with a sterile neutrino resulting in a
pair of mass eigenstates with a small mass gap. Using the density matrix
formalism we solve numerically the the evolution of neutrino states in the
envelope of a supernova and determine the flux ratios and
as a function of the active-sterile mixing angle and for the
experimentally allowed range of the standard active-active mixing angle
.Comment: 5 pages, 3 figures. This is the corrected version to be published in
Physical Review
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