$O(\alpha_S)$ Corrections to the Photon Structure Functions $F^\gamma_2(x,Q^2)$ and $F_L^\gamma(x,Q^2)$

Abstract

We examine the QCD corrections to the structure functions $F_2^\gamma(x,Q^2)$ and $F_L^\gamma(x,Q^2)$ for a real photon target. The pointlike photon contributions from light and heavy quarks are computed through $O(\alpha\alpha_S)$. A parameterization of the hadronic (resolved) photon contribution is also included and a comparison is made with the present experimental data. We find that while the pointlike contributions are large for $F_2^\gamma(x,Q^2)$, they are the dominant part of $F_L^\gamma(x,Q^2)$. For $Q^2 > 50$ $({\rm GeV}/c)^2$ the charm component is as least as large as the light quark component.