Charm production in deep inelastic scattering in the ZEUS experiment in the data-taking period of HERA-II

The ZEUS experiment is one of two general purpose colliding-beam experiments at the Hadron-Elektron-Ringanlage (HERA collider) at Deutsches Elektronensynchrotron (DESY), Hamburg. The ZEUS experiment has a new Micro-Vertex Detector (MVD) and Straw-Tube Tracker (STT), which have been in operation since the luminosity upgrade in 2001. Both components are part of a new global tracking system. This improved tracking has been used in a D*± analysis in deep inelastic scattering (DIS), in the kinematic range, 5<Q2<1000 GeV2 and 0.02<y<0.7. The D*±(2010) mesons are excited states containing charm and are produced at HERA in open-charm production in boson gluon fusion. The D*± have been investigated in the so-called golden channel, where the D*± decays via strong and weak interaction into a kaon and two pions: D*±→D0(→K-++π±)+π±S. The D*± mesons are identified using its invariant mass, which is calculated with the rest mass assumption and the momentum of the tracks. The total and differential cross sections have been calculated using Monte Carlo simulations. They have been compared with theoretical fixed-flavor-number-scheme (FNNS) next-to-leading order (NLO) predictions. That is a direct test of the gluon density function calculated with that theoretical model. Furthermore the cross-section measurements are the presupposition to determine the charm contribution to the structure function of the proton. (orig.)