5 research outputs found
Probing the neutrino mass hierarchy and the 13-mixing with supernovae
Get PDFWe consider in details the effects of the 13-mixing (sin^2 theta_{13}) and of
the type of mass hierarchy/ordering (sign[ Delta m^2_{13}]) on neutrino signals
from the gravitational collapses of stars. The observables (characteristics of
the energy spectra of nu_e and antinu_e events) sensitive to sin^2 theta_{13}
and sign[Delta m^2_{13}] have been calculated. They include the ratio of
average energies of the spectra, r_E = /, the ratio of widths of
the energy distributions, r_Gamma, the ratios of total numbers of nu_e and
antinu_e events at low energies, S, and in the high energy tails, R_{tail}. We
construct and analyze scatter plots which show the predictions for the
observables for different intervals of sin^2 theta_{13} and signs of Delta
m^2_{13}, taking into account uncertainties in the original neutrino spectra,
the star density profile, etc.. Regions in the space of observables r_E,
r_Gamma, S, R_{tail} exist in which certain mass hierarchy and intervals of
sin^2 theta_{13} can be identified or discriminated. We elaborate on the method
of the high energy tails in the spectra of events. The conditions are
formulated for which sin^2 theta_{13} can be (i) measured, (ii) restricted from
below, (iii) restricted from above. We comment on the possibility to determine
sin^2 theta_{13} using the time dependence of the signals due to the
propagation of the shock wave through the resonance layers of the star. We show
that the appearance of the delayed Earth matter effect in one of the channels
(nu_e or antinu_e) in combination with the undelayed effect in the other
channel will allow to identify the shock wave appeareance and determine the
mass hierarchy.Comment: LaTeX, 56 pages, 12 figures; a few clarifications added; typos
corrected. Version to appear in JCA
