Resonance spin flavour precession and solar neutrinos

We examine the prospects for the resonance spin flavour precession as a sol ution to the solar neutrino problem. We study seven different realistic sol ar magnetic field profiles and, by numerically integrating the evolution eq uations, perform a fit of the event rates for the three types of solar neut rino experiments (Ga, Cl and SuperKamiokande) and a fit of the energy spect rum of the recoil electrons in SuperKamiokande. A chi(2) analysis shows tha t the quality of the rate fits is excellent for two of the field profiles a nd good for all others with chi(2)/d.o.f. always well below unity. Regardin g the fits for the energy spectrum, their quality is better than that for t he small mixing angle MSW solution of the solar neutrino problem, at the sa me level as that for the large mixing angle MSW solution but worse than tha t for the vacuum oscillations one. The experimental data on the spectrum ar e however largely uncertain especially in the high energy sector, so that i t is too early yet to draw any clear conclusions on the likeliest type of p article physics solution to the solar neutrino problem. (C) 2000 Elsevier S cience B.V. All rights reserved.