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Probing the neutrino mass hierarchy and the 13-mixing with supernovae

2003; Institute of Physics; Volume: 2003; Issue: 06 Linguagem: Inglês

10.1088/1475-7516/2003/06/009

1475-7516

Cecilia Lunardini, Alexei Yu. Smirnov,

Particle physics theoretical and experimental studies

We consider in detail the effects of the 13-mixing (sin2θ13) and of the type of mass hierarchy/ordering (sign[Δm213]) on neutrino signals from the gravitational collapses of stars. The observables (characteristics of the energy spectra of νe and e events) sensitive to sin2θ13 and sign[Δm213] have been calculated. They include the ratio of average energies of the spectra, rE≡⟨E⟩/⟨Ē⟩, the ratio of widths of the energy distributions, rΓ≡Γ/, the ratios of total numbers of νe and e events at low energies, S, and in the high energy tails, Rtail. We construct and analyse scatter plots which show the predictions for the observables for different intervals of sin2θ13 and signs of Δm213, taking into account uncertainties in the original neutrino spectra, the star density profile, etc. Regions in the space of observables rE, rΓ, S, Rtail exist in which certain mass hierarchy and intervals of sin2θ13 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 sin2θ13 can be (i) measured, (ii) restricted from below, (iii) restricted from above. We comment on the possibility to determine sin2θ13 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 (νe or e) in combination with the undelayed effect in the other channel will allow us to identify the shock wave appeareance and determine the mass hierarchy.