Parton distributions in the photon from γ∗γ and γ∗p scattering

Leading order parton distributions in the photon are extracted from the existing F2γ 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.