Photoproduction and electroproduction

Abstract

Various aspects of the electromagnetic interactions of hadrons (strongly interacting particles) are reviewed in these lectures. After a discussion of the properties of the electromagnetic current of the hadrons and the idea of vector meson dominance, the general features of photoproduction cross sections are presented and compared with the very similar behavior of purely strong interaction processes. Given this close similarity in behavior, particular photon induced reactions are then considered in some detail, illustrating the application of theoretical ideas used in treating both strong and electromagnetic processes. The particular subjects discussed in some detail are photoproduction of pions at low energy and partial wave analysis, Compton scattering, vector meson photoproduction and tests of the vector dominance model, and photoproduction of charged pions at high energy. In the second half of the lectures inelastic electron-nucleon scattering is the principal topic. After a presentation of the kinematics and structure functions of the nucleon, the principal results of the inelastic electron scattering experiments are given together with the evidence for the remarkable scaling behavior of the structure functions. This leads to a presentation of the parton model of point constituents of the nucleon and the interpretation of the experimental results in terms of the properties of the constituent partons. A different view of inelastic electron scattering in terms of strong interaction ideas is presented in the last two lectures. These concern the high energy behavior of the scattering and the application of duality concepts which tie the behavior of nucleon resonance electroproduction to the behavior of the deep inelastic scattering. This is a revised version of the 1971 Les Houches lecture notes by the author, to be published by Gordon and Breach, which were brought up to date after the International Symposium on Electron and Photon Interactions at High Energies, Cornell University, 1971.