Measurement of the cross-section ratio σ(ψ(2S)) / σ(J/ψ(1S)) in exclusive photoproduction at HERA.

• hab. Grzegorz Grzelak

Room: Room: B2.38 Abstract: During the seminar I will present new analysis performed with ZEUS data on exclusive vector meson photoproduction - measurement of the cross section ratio of two charmonia states: ψ(2S) and J/ψ(1S). The analysis was performed using muonic decay channels of the investigated vector mesons. The ratio of their production cross sections has been measured as a function of W (photon–proton centre-of-mass energy) and |t| (squared four-momentum transfer at the proton vertex) and compared to previous data in photoproduction and deep inelastic scattering and with predictions of QCD-inspired models of exclusive vector-meson production. Serdecznie zapraszamy dr hab. Katarzyna Grzelak prof. dr hab. Jan Królikowski prof. dr hab. Aleksander Filip Żarnecki