Theory of hard photoproduction

The author reviews the present theoretical understanding of photons and hard photoproduction processes, discussing the production of jets, light and heavy hadrons, quarkonia, and prompt photons in photon-photon and photon-hadron collisions. Virtual and polarized photons and prompt-photon production in hadron collisions are also discussed. The most important leading-order and next-to-leading-order quantum chromodynamics results are compiled in analytic form. A large variety of numerical predictions is compared to data from TRISTAN, LEP, and HERA and extended to future electron and muon colliders. The sources of all relevant results are collected in an extensive bibliography.