Inclusive D* production is measured in deep-inelastic ep scattering at HERA with the H1 detector. In addition, the production of dijets in events with a D* meson is investigated. The analysis covers values of photon virtuality 2< Q^2 <=100 GeV^2 and of inelasticity 0.05<= y <= 0.7. Differential cross sections are measured as a function of Q^2 and x and of various D* meson and jet observables. Within the experimental and theoretical uncertainties all measured cross sections are found to be adequately described by next-to-leading order (NLO) QCD calculations, based on the photon-gluon fusion process and DGLAP evolution, without the need for an additional resolved component of the photon beyond what is included at NLO. A reasonable description of the data is also achieved by a prediction based on the CCFM evolution of partons involving the k_T-unintegrated gluon distribution of the proton.
Visible cross section for inclusive D*+- production.
Visible cross section for inclusive D*+- production.
Visible cross section for inclusive D*+- production with two jets.
Differential photoproduction cross sections are measured for events containing D* mesons. The data were taken with the H1 detector at the ep collider HERA and correspond to an integrated luminosity of 51.1 pb-1. The kinematic region covers small photon virtualities Q^2 < 0.01 GeV^2 and photon-proton centre-of-mass energies of 171 < W_gammap < 256 GeV. The details of the heavy quark production process are further investigated in events with one or two jets in addition to the D* meson. Differential cross sections for D* jet production are determined and the correlations between the D* meson and the jet(s) are studied. The results are compared with perturbative QCD predictions applying collinear- or kt -factorisation.
Integrated cross section in the visible range for inclusive D* production photoproduction.
Integrated cross section in the visible range for D*+ other jet production photoproduction.
Integrated cross section in the visible range for D* tagged dijet photoproduction.
The inclusive production of D^{*+-}(2010) mesons in deep-inelastic scattering is studied with the H1 detector at HERA. In the kinematic region 1<Q^2<100 GeV^2 and 0.05<y<0.7 an e^+p cross section for inclusive D^(*+-) meson production of 8.50+- 0.42 (stat.)^(+1.21)_(-1.00) (syst.) nb is measured in the visible range p_(tD^*)>1.5 GeV and |\eta_(D^*)|<1.5. Single and double differential inclusive D^(*+-) meson cross sections are compared to perturbative QCD calculations in two different evolution schemes. The charm contribution to the proton structure, F_2^c(x,Q^2), is determined by extrapolating the visible charm cross section to the full phase space. This contribution is found to rise from about 10% at Q^2 = 1.5 GeV^2 to more than 25% at Q^2 = 60 GeV^2 corresponding to x values ranging from 5*10^(-5) to 3*10^(-3)$.
The inclusive cross section for D*+- production. The second DSYS error is related to the changes in efficiency obtained by using different Monte Carlo generators and varying the model parameters.
Single differential visible cross section as a function of W.
Single differential visible cross section as a function of PT.
The production of D*+-(2010) mesons in deep inelastic scattering has been measured in the ZEUS detector at HERA using an integrated luminosity of 37 pb^-1. The decay channels D*+ -> D0 pi+(+c.c.), with D0 -> K- pi+ or D0 ->K- pi- pi+ pi+, have been used to identify the D mesons. The e+p cross section for inclusive D*+- production with 1<Q^2<600 GeV^2 and 0.02<y<0.7 is 8.31 +- 0.31(stat.) +0.30-0.50(syst.) nb in the kinematic region 1.5< pT(D*+-)<15 GeV and |eta(D*+-)|<1.5. Differential cross sections are consistent with a next-to-leading-order perturbative-QCD calculation when using charm-fragmentation models which take into account the interaction of the charm quark with the proton remnant. The observed cross section is extrapolated to the full kinematic region in pT(D*+-) and eta(D*+-) in order to determine the charm contribution, F^ccbar_2(x,Q^2), to the proton structure function. The ratio F^ccbar_2/F_2 rises from ~10% at Q^2 ~1.8 GeV^2 to ~30% at Q^2 ~130 GeV^2 for x values in the range 10^-4 to 10-3.
The measured cross section for D* production. The first is derived from theK2PI final state and the second from the K4PI final state.
The differential cross section w.r.t. Q**2 from the K2PI final state. The asymmetric errors are the quadratic sum of the statistical and systematic errors. The statistical errors are also shown separately.
The differential cross section w.r.t. X from the K2PI final state. The asymmetric errors are the quadratic sum of the statistical and systematic errors. The statistical errors are also shown separately.