Neutrino conversions in random magnetic fields and (nu)over-tilde(e) from the Sun - art. no. 063001

The magnetic field in the convective zone of the Sun has a random small-sca le component with the rms value substantially exceeding the strength of a r egular large-scale field. For two Majorana neutrino flavors x two helicitie s in the presence of a neutrino transition magnetic moment and nonzero neut rino mixing we analyze the displacement of the allowed (Delta-m(2)-sin(2)-2 -theta)-parameter region reconciled for the SuperKamiokande (SK) and radioc hemical (GALLEX, SAGE, Homestake) experiments in dependence on the rms magn etic field value b, or more precisely, on a value mu b assuming the transit ion magnetic moment mu = 10(-11) mu(B). In contrast with resonant spin-flav or precession in regular magnetic fields we find an effective production of electron antineutrinos in the Sun even for small neutrino mixing through t he cascade conversions nu(eL)-->nu(mu-L)-->(nu)over-tilde(eR), nu(eL)-->(nu )over-bar(eR) in a random magnetic field that would be a signature of the M ajorana nature of neutrino if (nu)over-tilde(eR) will be registered. Based on the present SK bound on electron antineutrinos we also find an excluded area in the same Delta-m(2),sin(2)-2-theta plane and reveal a strong sensit ivity to the random magnetic field correlation length L-0. [S0556-2821(99)0 0804-8].