Single Photon Searches at PEP

The MAC and ASP searches for events with a single photon and no other observed particles are reviewed. New results on the number of neutrino generations and limits on selectron, photino, squark and gluino masses from the ASP experiment are presented. Presented at the SLAC Summer Institute on Particle Physics Stanford, California, July 29 August 9, 1985 * Work supported by the Department of Energy, contract DE A CO3 76s F005 15. Introduction During the past year, two experiments have been carried out at PEP to search for events with a photon and large missing transverse momentum . These event searches are particularly sensitive to contributions from supersymmetric photino production but can also be used to search for additional neutrino generations, supersymmetric weak -charged currents or the production of any other neutral particle whose interactions in matter are of the order of the weak interaction. The MAC collaboration began modifications of their apparatus during the summer of 1983 to be able to detect photon events with no other observed charged or neutral particles. At the same time, a new experiment, ASP, was approved for installation at the PEP ring to do a high sensitivity search for such events. Single Photon Sources In the standard model of weak and electromagnetic interactions, events with a single photon and no other observed particles will be produced by radiative corrections to the production of neutrino pairs.