F/W e+e- INTERACTIONS*

INTRODUCTION The field of e+e-interactions has provided a great deal of excitement in the past few years. 1-9 Primarily, interest has centered around the reaction +-ee-hadrons. This reaction is particularly attractive because we believe in electromagnetic perturbation theory, which implies that the cross section for hadron production is dominated by one photon annihilation of the electron and positron. As a consequence of the single photon intermediate state the quantum numbers of the hadronic system are well defined, a nearly unique situation in hadron physics. The hadronic state must share the spin, parity, and charge conjugation assignment of the photon, J PC = I-. A unique property of e+e-physics with a storage ring is that the experiment is performed in the center of mass. This means that the total energy and momentum are known as well. A particular advantage over pp experiments is that the baryon number is zero, resulting in a considerable simplification of the final state. Thus the e+e-system is a particularly convenient probe to study photon-hadron coupling. In the first two lectures we shall discuss the total cross section for hadron production and scale invariance as applied to e+e-annihilation. The second two lectures will concentrate on the narrow Z) resonances at 3.095 and 3.684 GeV; the general properties as well as specific decay modes will be discussed,, Please note that I shall discuss mainly results from SLAC and DESY since Dr. Paoluzi will discuss results from Frascati. Also, where possible, reliance will be placed upon parallel lectures given by Drs. Nachtmann, and Appelquist to develop some subjects more thoroughly than these lectures allow. The bibliography is not intended to be exhaustive but rather should provide good background material, which in turn will have references for further study. Lastly, these lectures are frankly tutorial and are not intended to be a definitive review for specialists.-3-TOTAL CROSS SECTION The photon propagator enters into very many forms of physics. The accuracy which is required for knowledge of the propagator sometimes is beyond the lowest order result. The fact that the photon interacts with the rest of the world can produce subtle or even dramatic effects on its propagator. The coupling between the photon's interactions and the effect on the propagator may be expressed through a dispersion relation. D(s) = (l/s)/(l-n(s)). (1) Eq. (1) describes the photon propagator D as a function of s , the square of the photon's four-momentum. The …