D*production frome+e−toepcollisions in NLO QCD

Fragmentation functions for $D$ mesons, based on the convolution of a perturbative part, related to the heavy quark perturbative showering, and a nonperturbative model for its hadronization into the meson, are used to describe $D^{*}$ production in $e^{+}{e}^{-}$ and $\mathrm{ep}$ collisions. The nonperturbative part is determined by fitting the $e^{+}{e}^{-}$ data taken by ARGUS and OPAL at 10.6 and 91.2 GeV, respectively. When fitting with a nonperturbative Peterson fragmentation function and using next-to-leading evolution for the perturbative part, we find an ε parameter significantly different from the one commonly used, which is instead found with a leading order fit. The use of this new value is shown to increase considerably the cross section for $D^{*}$ production at DESY HERA, suggesting a possible reconciliation between the next-to-leading order theoretical predictions and the experimental data.