Hadronic Component of the Photon Spin Dependent Structure Function $g_1^{\gamma }$ from QCD

Abstract

We calculate the spin dependent structure function of the polarized virtual photon $g_1^{\gamma }(x,Q^2,p^2)$, especially its hadronic part, using the OPE in the inverse powers of the target photon virtuality. Some model is accepted to achieve a correct analytical behaviour in the photon squared mass. This enables extrapolation to the case of a real photon.

Comments: 12 pages, Latex, 1 Postscript figure, uses epsf.sty. The applicability region of the final formula are re-analyzed