Parton distributions in the photon from $\gamma^* \gamma$ and $\gamma^* p$ scattering

Abstract

Leading order parton distributions in the photon are extracted from the existing $F_2^\gamma$ measurements and the low-$x$ proton structure function. The latter is related to the photon structure function by assuming Gribov factorization to hold at low $x$. The resulting parton distributions in the photon are found to be consistent with the Frankfurt-Gurvich sum rule for the photon.