The polarized photon structure function $g_1^\gamma(x,Q^2)$ in massive   parton model in NLO
  We investigate the one-gluon-exchange ($\alpha \alpha_s$) corrections to the polarized real photon structure function $g_1^\gamma(x,Q^2)$ in the massive parton model. We employ a technique based on the Cutkosky rules and the reduction of Feynman integrals to master integrals. The NLO contribution is noticeable at large $x$ and does not vanish at the threshold of the massive quark pair production due to the Coulomb singularity. It is found that the first moment sum rule of $g_1^\gamma$ is satisfied up to the NLO. 
Norihisa Watanabe, Yuichiro Kiyo, Ken Sasaki
hep-ph