Solutions to Solar Neutrino Anomaly

Abstract

We present an updated analysis of astrophysical solutions, two-flavor MSW solutions, and vacuum oscillation solutions to the solar neutrino anomaly. The recent results of each of the five solar neutrino experiments are incorporated, including both the zenith angle (day-night) and spectral information from the Kamiokande experiment, and the preliminary Super-Kamiokande results. New theoretical developments include the use of the most recent Bahcall-Pinsonneault flux predictions (and uncertainties) and density and production profiles, the radiative corrections to the neutrino-electron scattering cross section, and new constraints on the Ga absorption cross section inferred from the gallium source experiments. From a model independent analysis, arbitrary astrophysical solutions are excluded at more that 98% C.L. even if one ignores any one of the three classes of experiment, relaxes the luminosity constraint, or allows more suppression of the 7Be than 8B flux. The data is well described by large and small mixing angle two-flavor MSW conversions, MSW conversions into a sterile neutrino with small mixing, or vacuum oscillations. We also present MSW fits for nonstandard solar models parameterized by an arbitrary solar core temperature or arbitrary 8B flux.