Electron capture on ^{8}B nuclei and Superkamiokande results

Abstract

The energy spectrum of recoil electrons from solar neutrino scattering, as observed by Superkamiokande, is deformed with respect to that expected from SSM calculations. We considered ν-e scattering from neutrinos produced by the electron-capture on ^{8}B nuclei, e^{-}+^{8}B --> ^{8}Be^{*}+ν_{e}, as a possible explanation of the spectral deformation. A flux Φ_{eB}\simeq 10^{4} cm^{-2} s^{-1} could account for Superkamiokande solar neutrino data. However this explanation is untenable, since the theoretical prediction, Φ_{eB}=(1.3+-0.2) cm^{-2} s^{-1}, is smaller by four orders of magnitude.