Charm in photoproduction at HERA

Inclusive differential cross-sections for D* production at HERA with respect to p(T)(D*) and eta(D*) are presented and compared to NLO QCD calculations in both the "massive" and "massless" schemes. There is significant disagreement between the various NLO calculations, none of which adequately describe the data, particularly for forward eta(D*). The differential cross-section d sigma(ep --> D* X)/dx(gamma)(OBS) for dijet production with charm is presented for the first time. This illustrates direct evidence for a significant contribution to charm production from resolved (x(gamma)(OBS) < 0.75) photoproduction at HERA, which is not described by a NLO calculation using the massive scheme. Comparison with LO Monte Carlo shows this is largely attributable to charm excitation below the photon factorization scale.