Long-wavelength vacuum neutrino oscillations and the solar-neutrino deficit

Vacuum neutrino oscillations with very long wavelengths, comparable to the radius of the Earth’s orbit, can simultaneously explain both the Homestake and Kamiokande-II solar-neutrino counting rates. They imply approximately a 50% reduction in the ${\nu }_{\mathit{e}}$ flux from the p-p process, and seasonal variations in the ν-e scattering rates for ${}_{}{}^7{}_{}{}^{}\mathrm{Be}$ and pep neutrinos, which distinguish this scenario from alternative explanations.