A non-resonant dark-side solution to the solar neutrino problem

We reanalyse spin-flavour precession solutions to the solar neutrino proble m in the light of the recent SNO CC result as well as the 1258-day Super-Ka miokande data and the upper limit on solar anti-neutrinos. In a self-consis tent magnetohydrodynamics approach the resulting scheme has only 3 effectiv e parameters: Deltam(2), muB(perpendicular to) and the neutrino mixing angl e theta. We show how a rates-only analysis for fixed muB(perpendicular to) slightly favours spin-flavour precession (SFP) solutions over oscillations (OSC). In addition to the resonant solution (RSFP for short), there is a ne w non-resonant solution (NRSFP) in the "dark-side". Both RSFP and NRSFP lea d to flat recoil energy spectra in excellent agreement with the latest Supe r-Kamiokande data. We also show that in the presence of a neutrino transiti on magnetic moment of 10-(11) Bohr magneton, a magnetic field of 80 KGauss eliminates all large mixing solutions other than the so-called LMA solution . (C) 2001 Elsevier Science B.V. All rights reserved.