Neutrino conversions in random magnetic fields and $\tildeν_e$ 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 ($Δm^2- \sin^22θ$)-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 $μb$ assuming the transition magnetic moment $μ= 10^{-11}μ_B$. 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 $ν_{eL}\to ν_{μL}\to \tildeν_{eR}$, $ν_{eL}\to ν_{μR}\to \tildeν_{eR}$ in a random magnetic field that would be a signature of the Majorana nature of neutrino if $\tildeν_{eR}$ will be registered. Basing on the present SK bound on electron antineutrinos we have also found an excluded area in the same $Δm^2,~\sin^22θ$-plane and revealed a strong sensitivity to the random magnetic field correlation length $L_0$.