12 research outputs found
Nature of neutrinos in the light of present and future experiments
Two general models with hierarchical and almost degenerate neutrino masses, which are able to explain the solar and atmospheric anomalies are investigated. We show how neutrinoless double beta decay experiments discern Dirac and Majorana natures of neutrinos. The strongest result is, that almost degenerate neutrinos with masses above 0.22 eV combined with the SMA MSW must be Dirac particles. In the general case, the same bound is true for specific parity assignments. In the near future (GENIUS experiment), one of the hierarchical schemes, and the VO mechanism for almost degenerate neutrinos and specific mixing matrix elements and parity assignments will be tested
Confronting electroweak precision measurements with New Physics models
Precision experiments, such as those performed at LEP and SLC, offer us an
excellent opportunity to constrain extended gauge model parameters. To this
end, it is often assumed, that in order to obtain more reliable estimates, one
should include the sizable one--loop Standard Model (SM) corrections, which
modify the couplings as well as other observables. This conviction is
based on the belief that the higher order contributions from the ``extension
sector'' will be numerically small. However, the structure of higher order
corrections can be quite different when comparing the SM with its extension,
thus one should avoid assumptions which do not care about such facts. This is
the case for all models with . As an example, both the manifest
left-right symmetric model and the model, with an additional boson, are discussed and special
attention to the top contribution to is given. We conclude that
the only sensible way to confront a model with the experimental data is to
renormalize it self-consistently, if not, parameters which depend strongly on
quantum effects should be left free in fits, though essential physics is lost
in this way. We should note that arguments given here allow us to state that at
the level of loop corrections (indirect effects) there is nothing like a
``model independent global analysis'' of the data.Comment: 10 page
Nature of neutrinos in the light of present and future experiments
Two general models with hierarchical and almost degenerate neutrino masses, which are able to explain the solar and atmospheric anomalies are investigated. We show how neutrinoless double beta decay experiments discern Dirac and Majorana natures of neutrinos. The strongest result is, that almost degenerate neutrinos with masses above 0.22 eV combined with the SMA MSW must be Dirac particles. In the general case, the same bound is true for specific parity assignments. In the near future (GENIUS experiment), one of the hierarchical schemes, and the VO mechanism for almost degenerate neutrinos and specific mixing matrix elements and parity assignments will be tested