Measurement of D* meson cross-sections at HERA and determination of the gluon density in the proton using NLO QCD

With the H1 detector at the ep collider HERA, D* meson production cross sections have been measured in deep inelastic scattering with four-momentum transfers Q^2>2 GeV2 and in photoproduction at energies around W(gamma p)~ 88 GeV and 194 GeV. Next-to-Leading Order QCD calculations are found to describe the differential cross sections within theoretical and experimental uncertainties. Using these calculations, the NLO gluon momentum distribution in the proton, x_g g(x_g), has been extracted in the momentum fraction range 7.5x10^{-4}< x_g <4x10^{-2} at average scales mu^2 =25 to 50 GeV2. The gluon momentum fraction x_g has been obtained from the measured kinematics of the scattered electron and the D* meson in the final state. The results compare well with the gluon distribution obtained from the analysis of scaling violations of the proton structure function F_2.

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27 pages, 9 figures, 2 tables, submitted to Nucl. Phys. B Report-no: DESY 98-204

positron p: colliding beams
positron p: deep inelastic scattering
D*(2010): electroproduction
D*(2010): photoproduction
D*(2010): hadronic decay
quantum chromodynamics: perturbation theory
differential cross section: transverse momentum
rapidity dependence
momentum transfer dependence
p: structure function

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