Open charm production at HERA

TL;DR

This paper reports measurements of open charm production at HERA, comparing experimental cross sections with QCD predictions, and provides new insights into charm fragmentation and photon-originated charm events.

Contribution

It presents the first measurement of the charm fragmentation function at HERA and compares various fragmentation ratios with e+e- results.

Findings

NLO QCD predictions are below measured data in some kinematic regions.

Clear evidence of charm originating from the incoming photon in dijet angular distributions.

First measurement of the charm fragmentation function at HERA.

Abstract

Inclusive charm meson production cross sections in the deep inelastic scattering and photoproduction regimes are compared with QCD leading and next-to-leading (NLO) calculations. The NLO predictions are significantly below the data in some parts of the measured kinematic range. Angular distributions of dijet events with charm show clear evidence for the existence of charm originating from the incoming photon. The charm fragmentation function is measured for the first time at HERA. Various fragmentation ratios and the fragmentation fractions of the low-lying charm hadrons are determined and compared to previous e+e- results.