9 research outputs found
Neutrino masses or new interactions
Recent proposals to study the mass of the "electron" neutrino at a
sensitivity of 0.3 eV can be used to place limits on the right handed and
scalar charged currents at a level which improves on the present experimental
limits. Indeed the neglect of the possibility of such interactions can lead to
the inference of an incorrect value for the mass, as we illustrate.Comment: 12 pages and 3 figures. Contributed to the XX International Symposium
on Lepton and Photon Interactions at High Energies, Rome, July 2001, and to
the International Europhysics Conference on High Energy Physics, Budapest,
July 2001. Preprint numbers added, misprints correcte
Neutrino clustering and the Z-burst model
The possibility that the observed Ultra High Energy Cosmic Rays are generated
by high energy neutrinos creating "Z-bursts" in resonant interactions with the
background neutrinos has been proposed, but there are difficulties in
generating enough events with reasonable incident neutrino fluxes.
We point out that this difficulty is overcome if the background neutrinos
have coalesced into "neutrino clouds" --- a possibility previously suggested by
some of us in another context. The limitations that this mechanism for the
generation of UHECRs places on the high energy neutrino flux, on the masses of
the background neutrinos and the characteristics of the neutrino clouds are
spelled out.Comment: 13 pages and 3 figures. Contributed to the XX International Symposium
on Lepton and Photon Interactions at High Energies, Rome, July 2001, and to
the International Europhysics Conference on High Energy Physics, Budapest,
July 2001. Preprint numbers added, misprints correcte
Dark Energy from Mass Varying Neutrinos
We show that mass varying neutrinos (MaVaNs) can behave as a negative
pressure fluid which could be the origin of the cosmic acceleration. We derive
a model independent relation between the neutrino mass and the equation of
state parameter of the neutrino dark energy, which is applicable for general
theories of mass varying particles. The neutrino mass depends on the local
neutrino density and the observed neutrino mass can exceed the cosmological
bound on a constant neutrino mass. We discuss microscopic realizations of the
MaVaN acceleration scenario, which involve a sterile neutrino. We consider
naturalness constraints for mass varying particles, and find that both ev
cutoffs and ev mass particles are needed to avoid fine-tuning. These
considerations give a (current) mass of order an eV for the sterile neutrino in
microscopic realizations, which could be detectable at MiniBooNE. Because the
sterile neutrino was much heavier at earlier times, constraints from big bang
nucleosynthesis on additional states are not problematic. We consider regions
of high neutrino density and find that the most likely place today to find
neutrino masses which are significantly different from the neutrino masses in
our solar system is in a supernova. The possibility of different neutrino mass
in different regions of the galaxy and the local group could be significant for
Z-burst models of ultra-high energy cosmic rays. We also consider the cosmology
of and the constraints on the ``acceleron'', the scalar field which is
responsible for the varying neutrino mass, and briefly discuss neutrino density
dependent variations in other constants, such as the fine structure constant.Comment: 26 pages, 3 figures, refs added, typos corrected, comment added about
possible matter effect
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Implications of Results of Neutrino Mass Experiments
The long standing negative (mass){sup 2} anomaly encountered in attempts to measure the mass of the electron neutrino may be an indication of physics beyond the standard model. It is demonstrated that an additional charged current interaction which is not of V--A form, and which is at least an order of magnitude weaker than the standard model charged current interaction, will produce a spectrum, which, if fitted by the standard model, may give a negative value for m{sub {nu}}{sup 2}. A possible physical explanation of the time dependent effects seen by the Troitsk experiment is also provided