Next-to-leading-order predictions for D^(*+-) plus jet photoproduction at DESY HERA

We study the photoproduction of a D^{*+-} meson in association with a hadron jet at next-to-leading order in the parton model of QCD with non-perturbative fragmentation functions extracted from LEP1 data of e^+e^- annihilation. The transverse-momentum and rapidity distributions recently measured at DESY HERA in various kinematic ranges nicely agree with our theoretical predictions. This provides a useful test of the universality and the scaling violations of the fragmentation functions predicted by the factorization theorem. These comparisons also illustrate the significance of the charm component in the resolved photon. This is elaborated by investigating the cross-section distributions in x_obs^gamma and cos(theta^*).