EPJ

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EPJ C - Particles and Fields
Particles and Fields
Eur. Phys. J. C 28, 437-449 (2003)
DOI: 10.1140/epjc/s2003-01201-x

Measurement of the inclusive D $^{*\pm}$ production in $\gamma\gamma$ collisions at LEP

The ALEPH Collaboration  


(Received: 13 January 2003 / Published online: 13 May 2003 )

Abstract
The inclusive production of D $^{*\pm}$ mesons in two-photon collisions is measured with the ALEPH detector at e+e- centre-of-mass energies from 183 GeV to 209 GeV. A total of $360 \pm 27$ D $^{*\pm}$ meson events are observed from an integrated luminosity of $699{\rm pb}^{-1}$. Contributions from direct and single-resolved processes are separated using the ratio of the transverse momentum $p_{\rm t}^{\rm D^{*\pm}}$ of the D $^{*\pm}$ to the visible invariant mass Wvis of the event. Differential cross sections of D $^{*\pm}$ production as functions of $p_{\rm t}^{\rm D^{*\pm}}$ and the pseudorapidity $\vert\eta^{\rm D^{*\pm}}\vert $ are measured in the range $ 2 {\rm GeV}/c < p_{\rm t}^{\rm D^{*\pm}} < 12 {\rm GeV}/c $ and $ \vert\eta^{\rm D^{*\pm}}\vert < 1.5 $. They are compared to next-to-leading order (NLO) perturbative QCD calculations. The extrapolation of the integrated visible D $^{*\pm}$ cross section to the total charm cross section, based on the Pythia Monte Carlo program, yields $ \sigma (\mathrm{e}^+\mathrm{e}^-\rightarrow \mathrm{e}^+\mathrm{e}^- \mathrm{... ...pm 74_{\mathrm{stat}} \pm 47_{\mathrm{syst}} \pm 157_{\mathrm{extr}} {\rm pb} $ .



© Società Italiana di Fisica, Springer-Verlag 2003

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