New NLO parameterizations of the parton distributions in real photons

We present new next-to-leading-order (NLO) sets of parton distributions in real photons based on a scheme-invariant definition of the non-perturbative input. We compare the theoretical predictions with LEP data and a best fit allows us to constrain the parameters of the distributions. The shape of the gluon distribution is poorly constrained and we consider the possibility to measure it in photoproduction experiments. Three parameterizations that aim to take into account the scattering of the LEP data are proposed and compared to other NLO parameterizations. (orig.)