Eur. Phys. J. C 22, 289-301 (2001)
DOI: 10.1007/s100520100805
Inclusive D* production in photon-photon collisions at next-to-leading order QCD
G. Kramer and H. SpiesbergerII. Institut für Theoretische Physik$^*$, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany Institut für Physik, Johannes-Gutenberg-Universität, Staudinger Weg 7, 55099 Mainz, Germany
(Received: 25 September 2001 / Published online: 5 November 2001 - © Springer-Verlag / Società Italiana di Fisica 2001)
Abstract
The next-to-leading order cross section for the inclusive production of
charm quarks in
collisions is calculated as a function
of the transverse momentum
pT and the rapidity
y in approaches
using massive or massless charm quarks. For the direct cross section we
derive the massless limit from the massive theory with the result that
this limit differs from the massless version with
factorization by finite corrections. Subtracting or adding these
corrections allows us to compare the two approaches on equal footing. We
establish massless and massive versions with 3 and 4 initial flavours
which are shown to approach the massless approximations very fast with
increasing
pT. With these results we calculate the inclusive
cross section in
collisions using realistic
evolved fragmentation functions with appropriate factorization scales
and compare with recent data for
from three LEP
collaborations after single- and double-resolved contributions have been
added.
© Società Italiana di Fisica, Springer-Verlag 2001
