Study of narrow baryonic pentaquark candidates with the ZEUS detector at HERA

The three pentaquark candidates Theta^+(1530), Xi(1862) and Theta^0_c(3100) have been studied in ep collisions at a centre-of-mass energy sqrt{s}=300-318 GeV using the full luminosity of the HERA-I data. Searches for narrow baryonic states in the decay channels K^0_s p, K^+ p, Xi^- pi^{+-}, anti-XI^+ pi^{+-} and D^{*+-}p^{-+} are reported. The results support the existence of a narrow resonance decaying into K^0_s p and K^0_s anti-p, consistent with the Theta(1530) state. No signals are seen in the K^+ p, Xi^- pi^{+-}, anti-Xi^+ pi^{+-} and D^{*+-}p{-+} channels.Comment: 8 pages, 5 figures, International Workshop PENTAQUARK04, SPring-8, Japan, July 200

Heavy Quark Production and Spectroscopy at HERA

Production of final states containing open charm and beauty quarks at HERA is reviewed. Photoproduction (PHP) of the charm meson resonances D^*, D^0 and D_s, as well as D^* production in the deep inelastic scattering (DIS) regime, are measured and compared to QCD predictions. The excited charm mesons D^0_1(2420), D^{*0}_2(2460) and D^{+-}_{s1}(2536) have been observed and the rates of charm quarks hadronising to these mesons were extracted. A search for radially excited charm mesons has been performed. PHP and DIS beauty cross sections are higher than expected in next-to-leading order QCD.Comment: 10 pages, 6 figures, 9th International Conference on Hadron Spectroscopy, Protvino, Russia, August 200