$e^{+}$ $e^{-}$ : Survey of Experimental Results

As the PETRA and PEP rings continue to run at high energies, the data on weak-electromagnetic inferences improve in accuracy. In particular, the forward- backward asymmetry results’ for the lepton pair reactions, $e^{+}$ $e^{-}$ $\longrightarrow$ $e^{+}$ $e^{-}$, $\mu^{+}$ $\mu^{-}$ $\tau^{+}$ $\tau^{-}$, now provide measurements of the Weinberg angle that are comparable in accuracy to values obtained from neutrino experiments. The agreement with the accepted $sin^{2}$ $0_{w}$ = 0.22 is excellent. Our experimental picture of tau decays is becoming rather detailed. There are many measurements of the $\tau$ lifetime, all from $e^{+}$ $e^{-}$ experiments.