Photonic parton distributions beyond the leading order. Heavy quark and dilepton production at ep colliders

The significance of the photonic parton distributions fγ=(qγ, Gγ) at ep colliders is illustrated for two inclusive processes suitable for a separate determination of Gγ and qγ. It is furthermore shown that the expected production rates are perturbatively stable provided the higher order qγ(x, μ2) distributions at x≅1 behave as recently suggested, in order to avoid the large-x instability problems of the photon structure function. (orig.)