Higher orders and IR renormalon phenomenology in DVCS

Abstract

We present results for higher order perturbative corrections to Compton scattering in the generalized Bjorken kinematics. The approach we have used is based on the combination of two techniques: conformal operator product expansion on the one side, and resummation of the fermion vacuum insertions with consequent restoration of the full QCD beta-function via the naive nonabelianization assumption, on the other. These are terms which are lost in the former approach. Due to the presence of the infrared renormalon poles in the Borel transform of the resummed amplitude the latter suffers from ambiguities which reflect the asymptotic character of perturbation series. The residues of these IR renormalon poles give an estimate for the size of power corrections in deeply virtual Compton scattering.