Photoproduction of D-*+/- mesons in electron-proton collisions at HERA

At the electron-proton collider HERA the inclusive D-*+/- meson photoproduction cross section has been measured with the H1 detector in two different, but partly overlapping, kinematical regions. For the first, where [W-gamma p] approximate to 200 GeV and Q(2) < 0.01 GeV2, the result is sigma(gamma p --> c(c) over barX$) = (13.2 +/- 2.2(-1.7-4.8)(+2.1+9.9)) mu b. The second measurement for Q(2) < 4 GeV2 yields sigma(gamma p) --> c(c) over barX$) = (9.3 +/- 2.1(-1.8-3.2)(+1.9+6.9)) mu b at [W-gamma p] approximate to 142 GeV and sigma(gamma p --> c(c) over barX$) = (20.6 +/- 5.5(-3.9-7.2)(+4.3+15.4)) mu b at [W-gamma p] approximate to 230 GeV, respectively. The third error accounts for an additional uncertainty due to the proton and photon parton density parametrizations. Differential cross sections are presented as a function of the D-*+/- transverse momentum and rapidity. The results compare reasonably well with next-to-leading order QCD calculations. Evidence for diffractive photoproduction of charm quarks is presented.