A Search for Oscillations at SuperKamiokande-I

Super-Kamiokande (SK)is a 50 kton ring imaging water cherenkov counter located in Mozumi Japan and designed to study neutrino physics and baryon number violation. Here we summarize a search for neutron-antineutron oscillations using the full 1489.2 day SK-I data set. The results of our search include a 90 % confidence level (CL) lower limit on the lifetime for neutron oscillation in Oo f , a factor of 4 improvement over the previous best oscillation limits for neutrons bound inside nuclei. Using a nuclear suppression factor of , our new limit corresponds to a free neutron oscillation limit of seconds, an improvement of a factor of 2.7 over the previous best free neutron limit of seconds, as reported by the ILL reactor experiment (at Grenoble). These new resultsmay constrain some theories involving grand unification and supersymmetry particularlythose inolving right-left symmetry and the see-saw mechanicsm such as SO(10)