C. Adloff et al., Measurement of D* meson cross sections at HERA and determination of the gluon density in the proton using NLO QCD, NUCL PHYS B, 545(1-3), 1999, pp. 21-44
With the H1 detector at the ep collider HERA, D* meson production cross sec
tions have been measured in deep inelastic scattering with four-momentum tr
ansfers Q(2) > 2 GeV2 and in photoproduction at energies around W-gamma p a
pproximate to x 88 GeV and 194 GeV, Next-to-Leading Order QCD calculations
are found to describe the differential cross sections within theoretical an
d experimental uncertainties. Using these calculations, the NLO gluon momen
tum distribution in the proton, x(g)g(x(g)), has been extracted in the mome
ntum fraction range 7.5 x 10(-4) < x(g) < 4 x 10(-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 f
inal state. The results compare well with the gluon distribution obtained f
rom the analysis of scaling violations of the proton structure function F-2
. (C) 1999 Elsevier Science B.V.