Beauty and Charm Production at HERA

Abstract

Recent measurements of charm and beauty production in ep collisions at HERA are presented. Measurements by ZEUS on the production of charm hadrons ( D ∗ + , D 0 , D + and Λ c + ) and their antiparticles in photoproduction are shown [ZEUS Collab., S. Chekanov et al., Eur. Phys. J. C 44 (2005), DESY-05-147]. Results on the ratio of neutral and charged charm mesons R u / d , the strangeness-suppression factor γ s and the fraction of charged D mesons produced in a vector state, P v d , are given, as well the fraction of charm hadronising as a particular charm hadron ( c → D , Λ c ). The fraction of events containing charm and beauty quarks determined by H1 using a method based on the impact parameter, in the transverse plane, of tracks w.r.t. the primary vertex, are presented [H1 Collab., A. Aktas et al., Eur. Phys. J. C 45, 23-33 (2006)]. F 2 c c ¯ and F 2 b b ¯ are presented for values of the photon virtuality 12 Q 2 60 GeV 2 and the Bjorken scaling variable 0.0002 ⩽ x ⩽ 0.005 . The results are compared to predictions from perturbative quatum chromodynamics and with previous measurements of F 2 c c ¯ using D ∗ mesons and found compatible. A recent ZEUS measurement of the differential cross section d σ / d p T μ for the process e + p → e + + b b ¯ + X → e + + j j + μ + X also shows good agreement between data and the pQCD prediction [M. Corradi (H1 and ZEUS Collab.), “Heavy Quarks at Hera with Lifetime Tag”, Proceedings of HEP2005, 70 (2005)].