30,624 research outputs found
Determining See-Saw Parameters from Weak Scale Measurements?
The see-saw mechanism is a very attractive explanation for small neutrino
masses, parametrized at the GUT scale by the right-handed Majorana mass matrix,
, and the neutrino Yukawa matrix, . We show that in a
SUSY model with universal soft terms, and can be
calculated from the light neutrino masses, the MNS matrix, and , which enters into the left-handed slepton
radiative corrections. This suggests that in principle the GUT-scale inputs of
the seesaw could be reconstructed from the neutrino and sneutrino mass
matrices. We briefly discuss why this is impractical, but advocate the neutrino
and sneutrino mass matrices as an alternative bottom-up parametrization of the
seesaw.Comment: Version to be published. References added, modified abstract, minor
stylistic changes. Content unchange
Impact of radiative corrections on sterile neutrino scenarios
In sterile neutrino scenarios, radiative corrections induce mass splittings
proportional to the top Yukawa coupling, in contrast to the three active
neutrino case where the induced splittings are proportional to the tau Yukawa
coupling. In view of this, we have analyzed the stability of the four-neutrino
schemes favored by oscillation experiments, consisting in two pairs of nearly
degenerate neutrinos separated by the LSND gap. Requiring compatibility with
the measurements of the abundances of primordial elements produced in Big Bang
Nucleosynthesis, we find that when the heaviest pair corresponds to the solar
neutrinos (mainly an admixture of nu_e - nu_s) the natural mass splitting is
3-5 orders of magnitude larger than the observed one, discrediting the scenario
from a theoretical point of view. On the contrary, the scheme where the
heaviest pair corresponds to the atmospheric neutrinos (mainly an admixture of
nu_mu - nu_tau) is safe from radiative corrections due to the small sterile
component of these mass eigenstates.Comment: 14 pages, LaTeX, 2 figures. Discussion enlarged, references added and
typos correcte
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