We show that the matrix element of a local quark-gluon operator in the photon state, <γ(kλ)∣O^∣γ(kλ)>, can be calculated in lattice QCD. The result is generalized to other quantities involving space-like photons, including the transition form factor γγ∗→π0 and the virtual-photon-nucleon Compton amplitude <γ∗N∣γ∗N> which can be used to define the generalized Drell-Hearn-Gerasimov and Bjorken sum rules.
@article{arxiv.hep-lat/0101014,
title = {Studying Hadronic Structure of the Photon in Lattice QCD},
author = {Xiangdong Ji and Chulwoo Jung},
journal= {arXiv preprint arXiv:hep-lat/0101014},
year = {2009}
}