QUANTUM-CHROMO DYNAMIC PREDICTIONS FOR DIRECT PHOTONS IN COLLISIONS

摘要

We analyze the direct photon production in e e collisions in quantum chromo dynamics using the cut vertex formalism and renormalization group method. The two-loop anomalous dimensions of time-like cut vertices are calculated from the two-loop parton decay probability functions. The moments of the transverse structure function WT are calculated up to the next-to-leading order. The no leading corrections to WT turn out to be large, and even larger than those to the photon structure function F2 in the photon-photon scattering. Also, the moments of the longitudinal structure function WL are calculated in the leading order. The corrections are found to be small.