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

Abstract At the electron-proton collider HERAthe inclusive D∗± mesonphotoproduction cross section has been measured with the H1 detector in two different, but partly overlapping, kinematical regions. For the first, where 〈 W γp 〉 ≈ 200 GeV and Q 2 2 , the result is σ(γp → c c X) = (13.2 ± 2.2 −1.7 −4.8 +2.1 +9.9 ) μ b . The second measurement for Q 2 2 yields σ(γp → c c X) = (9.3 ± 2.1 −1.8 −3.2 +1.9 +6.9 ) μ b at 〈Wγp〉 ≈ 142 GeV and σ(γp → c c X) = (20.6 ± 5.5 −3.9 −7.2 +4.3 +15.4 μ b at 〈Wγp〉 ≈ 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 quarksis presented.