Measurement of charm fragmentation fractions in photoproduction at HERA

A bstract The production of D 0 , D * + , D + , $ D_s^{+} $ and $ \Lambda_c^{+} $ charm hadrons and their antiparticles in ep scattering at HERA has been studied with the ZEUS detector, using a total integrated luminosity of 372 pb −1 . The fractions of charm quarks hadronising into a particular charm hadron were derived. In addition, the ratio of neutral to charged D -meson production rates, the fraction of charged D mesons produced in a vector state, and the stangeness-suppression factor have been determined. The measurements have been performed in the photoproduction regime. The charm hadrons were reconstructed in the range of transverse momentum p T > 3 . 8 GeV and pseudorapidity | η | < 1 . 6. The charm fragmentation fractions are compared to previous results from HERA and from e + e − experiments. The data support the hypothesis that fragmentation is independent of the production process.