e+e- annihilation

This paper presents several topics concerning positron-electron annihilation. The topics included are the status of resonance below 3 GeV, total cross sections, and inclusive D meson spectra at high energy. Comprehensive review of the properties of tau leptons is also described. Isospin 1 resonance will appear in the states with even numbers of pions. The experimental results are introduced, and resonance is clearly seen. Several new measurements of the ratio R of total hadronic cross section to muon pair production cross section are presented and compared. There is surprisingly good agreement among the experiments for general structure of the cross sections. The measurement of D meson energy spectra above the charmonium resonance region by the SLAC-LBL and LGW experiments has been presented. The review of tau properties includes the history, the branching fractions, the tau mass, the tau spin, the tau lifetime, the tau-ν coupling, the ν mass, and the type of lepton for the tau. Three possible tau decay modes are illustrated. The QCD correction gives some enhancement to the semihadronic final states and reduces the prediction for the electronic branching fraction to 18 percent. The tau mass was deduced from the energy dependence of the tau production cross section. If the tau does not have a form factor, all spin assignments except 1/2 are excluded. The upper limit of the lifetime of tau is about 3 x 10-12 sec. All of the evidences are consistent with the assumption that the tau is a sequential lepton decaying to its own massless neutrino with V - A coupling. (Kato, T.)