The Virtual Compton Amplitude in the Generalized Bjorken Region: Twist--2 Contributions
Abstract
A systematic derivation is presented of the twist-2 anomalous dimensions of the general quark and gluon light-ray operators in the generalized Bjorken region in leading order both for unpolarized and polarized scattering. Various representations of the anomalous dimensions are derived both in the non-local and the local light cone expansion and their properties are discussed in detail. Evolution equations for these operators are derived using different representations. General two- and single-variable evolution equations are presented for the expectation values of these operators for non-forward scattering. The Compton amplitude is calculated in terms of these distribution amplitudes. In the limit of forward scattering a new derivation of the integral relations between the twist-2 contributions to the structure functions is given. Special limiting cases which are derived from the general relations are discussed, as the forward case, near-forward scattering, and vacuum-meson transition. Solutions of the two-variable evolution equations for non-forward scattering are presented.
Keywords
Cite
@article{arxiv.hep-ph/9903520,
title = {The Virtual Compton Amplitude in the Generalized Bjorken Region: Twist--2 Contributions},
author = {J. Blümlein and B. Geyer and D. Robaschik},
journal= {arXiv preprint arXiv:hep-ph/9903520},
year = {2008}
}
Comments
52 pages LATEX, published version in Nucl. Phys. B