Solar-neutrino-oscillation parameters and the broken-R-parity Majoron

Matter-enhanced neutrino-oscillation parameters can be probed in a variety of conventional experiments in supergravity models where the small neutrino mass arises from spontaneous R-parity violation. A combined analysis of astrophysical and laboratory limits tends to exclude regions of oscillation parameters where the high-energy neutrinos are adiabatically converted. This suggests the possibility of a large reduction in the pp and ${}_{}{}^7{}_{}{}^{}\mathrm{Be}$ neutrino flux even for a mildly reduced ${}_{}{}^8{}_{}{}^{}\mathrm{B}$ neutrino flux, thus stressing the importance of gallium experiments.