Neutrino conversions in random magnetic fields and ${\tilde{\nu }}_e$ from the Sun

Abstract

The magnetic field in the convective zone of the Sun 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 $b$, or more precisely, on a value $\mu b$ assuming the transition magnetic moment $\mu =10^{-11}{\mu }_B$. In contrast to RSFP in regular magnetic fields we find an effective production of electron antineutrinos in the Sun even for small neutrino mixing through cascade conversions ${\nu }_{eL}\to {\nu }_{\mu L}\to {\tilde{\nu }}_{eR}$, ${\nu }_{eL}\to {\nu }_{\mu R}\to {\tilde{\nu }}_{eR}$ in a 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 have also found an excluded area in the same $\Delta m^2,{\sin }^{2}2\theta$-plane and revealed a strong sensitivity to the random magnetic field correlation length $L_0$.

Comments: LaTex 36 pages including 14 PostScript figures