24–30 Sept 2022
Corigliano Calabro, Italy
Europe/Rome timezone

Measurement of the cross-section ratio sigma(psi(2S))/sigma(J/psi(1S)) in exclusive photoproduction at HERA

27 Sept 2022, 08:50
20m
Corigliano Calabro, Italy

Corigliano Calabro, Italy

BV Airone Resort
Low x, PDFs and hadronic final states Low x, PDFs and hadronic final states

Speaker

Grzegorz Grzelak

Description

On behalf of the ZEUS Collaboration.
Submitted to JHEP.

The exclusive photoproduction reactions gamm p -> J/psi(1S) p and gamma p -> psi(2S) p have been measured at an ep centre-of-mass energy of 318 GeV with the ZEUS detector at HERA using an integrated luminosity of 373 pb-1. The measurement was made in the kinematic range 30 < W < 180 GeV, Q^2 < 1 GeV^2 and |t| < 1 GeV^2, where W is the photon–proton centre-of-mass energy, Q^2 is the photon virtuality and t is the squared four-momentum transfer at the proton vertex. The decay channels used were J/psi(1S) -> mu+mu−, psi(2S) -> mu+mu− and psi(2S) -> J/psi(1S)pi+pi− with subsequent decay J/psi(1S) -> mu+mu−. The ratio of the production cross sections, R = sigma(psi(2S))/sigma(J/psi(1S)), has been measured as a function of W and |t| and compared to previous data in photoproduction and deep inelastic scattering and with predictions of QCD-inspired models of exclusive vector-meson production, which are in reasonable agreement with the data.

Presentation materials