Virtual corrections for electron--positron annihilation into one real and one off-shell photon of invariant mass Q^2 are evaluated. Special attention is paid to those configurations where the real photon is collinear with the beam direction. This calculation is an important ingredient of a Monte Carlo program, which simulates events with tagged photons from initial-state radiation, including NLO corrections.
@article{arxiv.hep-ph/0204283,
title = {The radiative return at small angles: virtual corrections},
author = {Johann H. Kuhn and German Rodrigo},
journal= {arXiv preprint arXiv:hep-ph/0204283},
year = {2009}
}