QCD CORRECTIONS TO PHOTON PRODUCTION IN ASSOCIATION WITH HADRONS IN E+E- ANNIHILATION

Next-to-leading order QCD corrections for inclusive photon production in e+ e- annihilation are derived. We emphasize that in a well-defined perturbative analysis - with or without isolation - it is always necessary to subtract the photon-quark collinear singularity. The subtraction term is absorbed into the non-perturbative fragmentation functions of the photon. The Q2-dependence of the photon fragmentation functions is determined by inhomogeneous evolution equations. The modification of the evolution equations due to photon isolation is discussed. We also analyse the validity of the approaches where the non-perturbative contributions are neglected. Using a general purpose next-to-leading order Monte Carlo program, we calculate various physical quantities that were measured in LEP experiments recently.