ARE THERE STERILE NEUTRINOS IN THE FLUX OF SOLAR NEUTRINOS ON THE EARTH?

Abstract

It is shown that the future SNO and Super-Kamiokande experiments, in which high energy $^8\mathrm{B}$ neutrinos will be detected through the observation of CC, NC and $ν$--$e$ elastic scattering processes, could allow to reveal in a model independent way the presence of sterile neutrinos in the flux of solar neutrinos on the earth. Lower bounds for different averaged values of the probability of transition of solar $ν_e$'s into sterile states and for the total flux of $^8\mathrm{B}$ neutrinos are derived in terms of measurable quantities. The possibilities to reveal the presence of $ν_μ$ and/or $ν_τ$ in the solar neutrino flux on the earth are also considered and the case of transitions of solar $ν_e$'s only into sterile states is discussed. Some numerical results for a simple model with $ν_e$--$ν_s$ mixing are given.