DOI: 10.1140/epjc/s2002-01100-8
Unintegrated gluon in the photon and heavy quark production
L. Motyka1, 2 and N. Tîmneanu11 High Energy Physics, Uppsala University, Box 535, 751 21 Uppsala, Sweden
2 Institute of Physics, Jagellonian University, Reymonta 4, 30-059 Kraków, Poland
(Received: 4 September 2002 / Revised version: 6 November 2002 / Published online: 20 December 2002 )
Abstract
The unintegrated gluon density in the photon is determined,
using the Kimber-Martin-Ryskin prescription.
In addition, a model of the unintegrated gluon is
proposed, based on the saturation model extended to the
large-
x region. These gluon densities are applied to obtain
cross sections for charm and bottom production in
and
collisions using the
kt factorization
approach. We investigate both direct and resolved photon
contributions and make a comparison with
the results from the collinear approach and the experimental
data.
An enhancement of the cross section due to inclusion
of non-zero transverse momenta of the gluons is found.
The charm production cross section is consistent with the
data. The data exceed our conservative estimate for bottom
production in
collisions, but theoretical uncertainties
are too large to claim a significant inconsistency.
A substantial discrepancy between theory and the experiment
is found for
, which
is not cured by
the
kt factorization approach.
© Società Italiana di Fisica, Springer-Verlag 2003