One-Loop Helicity Amplitudes for Parton Level Virtual Compton Scattering

Abstract

We calculate the one-loop QCD virtual corrections to all helicity amplitudes for parton level virtual Compton scattering processes. We include the amplitudes both on quark target process ${\gamma }^{\ast }q\to \gamma q$ and on gluon target process ${\gamma }^{\ast }g\to \gamma g$. The infrared pole structure of the amplitudes is in agreement with the prediction of Catani's general formalism for the singularities of one-loop amplitudes, while expressions for the finite remainder are given in terms of logarithms and dilogarithms that are real in the physical region.

Comments: 16 pages, 2 figures, detailed comparison with DVCS included