UC Irvine

After the discovery of neutrino oscillations by SuperKamiokande three years ago the measurements of their masses and flavor mixing are under way using various neutrino sources and energies. High precision data on atmospheric neutrinos show that the dominant mixings occur between active species. They allow for statistically significant three-flavor analysis, which confirm the almost maximal mixing v(mu) <----> v(tau). Results of searches for tau neutrinos are consistent with this scenario. The K2K experiment, which uses the KEK accelerator as the neutrino source and the SuperKamiokande for their detection, is sensitive to the oscillations observed in the atmospheric neutrinos. The results obtained after one year of the run time provide a check of the oscillation parameters with the well determined beam properties using a set of near detectors and beam monitors. The solution of the solar neutrino puzzle in terms of v, oscillations has been recently much enhanced by exciting new results from the SNO Collaboration. Their comparison with SuperKamiokande results again excludes a sterile neutrino mixing as dominant suggesting instead a large v(e) mixing with other active neutrinos. This interpretation has been favored by recent SuperKamiokande spectral and angular measurements.

* Presented at the XXVII Mazurian Lake School of Physics, Krzyze, Poland, September 2-9, 2001.