Virtual Photon Structure Functions to NNLO in QCD

Abstract

The unpolarized virtual photon structure functions $F_2^\gamma(x,Q^2,P^2)$ and $F_L^\gamma(x,Q^2,P^2)$ are investigated in perturbative QCD for the kinematical region $\Lambda^2 \ll P^2 \ll Q^2$, where $-Q^2(-P^2)$ is the mass squared of the probe (target) photon and $\Lambda$ is the QCD scale parameter. In the framework of operator product expansion supplemented by the renormalization group method, the definite predictions are derived for the moments of $F_2^\gamma(x,Q^2,P^2)$ up to the next-to-next-to-leading order (the order $\alpha\alpha_s$) and for the moments of $F_L^\gamma(x,Q^2,P^2)$ up to the next-to-leading order (the order $\alpha\alpha_s$)