Aperiodic Spin-Flavor Conversions and ${\tilde{\nu }}_e$ from the Sun with Random Magnetic Field

Abstract

The magnetic field in the solar convective zone has a random small-scale component with the r.m.s. value substantially exceeding the strength of a regular large-scale field. For two Majorana neutrino flavors $\times$ two helicities in the presence of a neutrino transition magnetic moment and nonzero neutrino mixing we analyze the displacement of the allowed ($\Delta m^2-{\sin }^{2}2\theta$) - parameter region reconciled for the SuperKamiokande(SK) and radiochemical (GALLEX, SAGE, Homestake) experiments in dependence on the r.m.s. magnetic field value $b$. We find an effective production of electron antineutrinos in the Sun even for small neutrino mixing through the cascade conversions in the random magnetic field that would be a signature of the Majorana nature of neutrino if ${\tilde{\nu }}_{eR}$ will be registered. Basing on the present SK bound on electron antineutrinos we also estimated the corresponding excluded area in the plane $\Delta m^2,{\sin }^{2}2\theta$.

Comments: LaTex 10 pages, 5 PostScript figures included, Talk given at the EU Conference "New Trends in Neutrino Physics", Ringberg, May 1998