Joint analysis of Borexino and SNO solar neutrino data and reconstruction of the survival probability

Abstract

Solar neutrino oscillations are supported by KamLAND's antineutrino measurements, but certain solar neutrino data - the observed shape of the ${}^8$B flux and the difference between day and night counting rates measured in Super-Kamiokande - do not fit well with the ensuing oscillation pattern. Interestingly, other solar neutrino data allow independent tests of the survival probability. Thanks to the new measurements of Borexino at low-energies along with the standard solar model and to the results of SNO at high-energies, four values of the neutrino survival probability are known. We build and study a likelihood based only on these solar neutrino data. The results agree well with the standard oscillation pattern and in particular with KamLAND findings. A related and straightforward procedure permits to reconstruct the survival probability of solar neutrinos and to assess its uncertainties, for all solar neutrino energies.