https://doi.org/10.1140/epjc/s2005-02397-3
Experimental Physics
Measurement of charm fragmentation ratios and fractionsin photoproduction at HERA
The production of 
, D
0, D
+ , D
s
+ and 
charm hadrons and their antiparticles in e p scattering at HERA was measured with the ZEUS detector using an integrated luminosity of 
. The measurement has been performed in the photoproduction regime with the exchanged-photon virtuality 
and for photon-proton centre-of-mass energies in the range 
. The charm hadrons were reconstructed in the range of transverse momentum 
and pseudorapidity 
. The production cross sections were used to determine the ratio of neutral and charged D-meson production rates, 
, the strangeness-suppression factor, 
, and the fraction of charged D mesons produced in a vector state, 
. The measured and 
values agree with those obtained in deep inelastic scattering and in e
+
e
- annihilations. The measured value is smaller than, but consistent with, the previous measurements. The fractions of c quarks hadronising as a particular charm hadron, 
, were derived in the given kinematic range. The measured open-charm fragmentation fractions are consistent with previous results, although the measured 
is smaller and 
is larger than those obtained in e
+
e
- annihilations. These results generally support the hypothesis that fragmentation proceeds independently of the hard sub-process.
© Springer-Verlag, 2005
