Solar Neutrino Experiments: New Physics?

Physics beyond the simplest version of the standard electroweak model is required to reconcile the results of the chlorine and the Kamiokande solar neutrino experiments. None of the 1000 solar models in a full Monte Carlo simulation is consistent with the results of the chlorine or the Kamiokande experiments. Even if the solar models are forced articficially to have a ${}^8 B$ neutrino flux in agreement with the Kamiokande experiment, none of the fudged models agrees with the chlorine observations. This comparison shows that consistency of the chlorine and Kamiokande experiments requires some physical process that changes the shape of the ${}^8 B$ neutrino energy spectrum. The GALLEX and SAGE experiments, which currently have large statistical uncertainties, differ from the predictions of the standard solar model by $2 \sigma$ and $3 \sigma$, respectively. The possibility that the neutrino experiments are incorrect is briefly discussed.