Production of the excited charm mesons D1 and D*2 at HERA

The production of the excited charm mesons D1, D*2 and D+s1 in ep collisions has been measured with the ZEUS detector at Hera. The data sample taken by the ZEUS detector in the years 2003-2007, corresponding to an integrated luminosity of 373 pb-1 has been used. The masses of the neutral, charged and strange states, the widths of the neutral states, the helicity parameters of D01 and D+s1 were determined and compared with other measurements and with theoretical expectations. The measured helicity parameters of the D01 and D+s1 allows for some mixing of S- and D-waves in their decays to D*±π-+ and D*±K0 respectively. The measured value of the D01 helicity parameter is also consistent with a pure D-wave decay. Ratios of branching fractions of the two decay modes of the D*02, D*±2 and D+s1 states were measured and compared with previous measurements. The fractions of charm quarks hadronising into D1, D*2 and D+s1 were measured and are consistent with those obtained in e+e- annihilations. The Grid computing technology has a high importance for modern High Energy Physics. This technology has been successfully used in Zeus experiment for the MC simulations and data analysis. The dedicated infrastructure has been maintained by the author since 2010. In addition to continuous support, the author has upgraded and improved the performance of the Grid MC simulations and contributed to the Zeus data preservation project.