(T/E) c, b, AND T LIFETIME MEASUREMENTS IN e+e- INTERACTIONS*

January 1983 (T/E) c, b, AND T LIFETIME MEASUREMENTS IN e+eINTERACTIONS* . John A. Jaros Stanford Linear Accelerator Center INTRODUCTION Measurements of the lifetimes of weakly decaying particles let us infer the strength of the interaction responsible for their decay. Two features of these interactions have emerged from studies of the lighter quarks and leptons. First, the interactions have universal strength; and second, the weak interaction mixes the physical quark states. By measuring the lifetimes of the charmed particles, the tau lepton, and hadrons containing the bottom quark, we are testing universality in a new domain and investigating new examples of -. mixing. +e e annihilations are a suitable laboratory for these studies. The heavy flavors are produced in sufficient numbers for lifetime determinations and are relatively easy to identify against the light flavor background. At PEP/PETRA energies,lifetimes in the 10-l' to lo-l2 s range result in average decay lengths between 100 and 1000 u. The techniques which have been successful at measuring decay lengths -. in this range, notably high resolution bubble chambers and nuclear emulsion, are not easily adaptable to the e+estorage ring environment, with its megahertz repetition rates, occasional beam loss, and no-trespassing zone imposed by the beam pipe. However during the past two years, several of the PEP and PETRA experiments have begun