%0 Electronic Article
%T Measurement of the cross-section ratio σ<sub>ψ(2S )</sub>/σ<sub>J/ψ(1S )</sub> in exclusive photoproduction at HERA
%N DESY-22-107
%M PUBDB-2022-03175
%M DESY-22-107
%M arXiv:2206.13343
%D 2022
%Z To be submitted to JHEP
%X The exclusive photoproduction reactions γp → J/ψ(1S) p and γp → ψ(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<sup>−1</sup>.  The measurement was made in the kinematic range 30  <  W  <  180 GeV, Q<sup>2</sup>  <  1 GeV<sup>2</sup> and |t|  <  1 GeV<sup>2</sup>, where W is the photon-proton centre-of-mass energy, Q<sup>2</sup> is the photon virtuality and t is the squared four-momentum transfer at the proton vertex.  The decay channels used were J/ψ(1S) → μ<sup>+</sup> μ<sup>−</sup>,   ψ(2S) → μ<sup>+</sup> μ<sup>−</sup> and ψ(2S) → J/ψ(1S) π<sup>+</sup> π<sup>−</sup> with subsequent decay J/ψ(1S) → μ<sup>+</sup> μ<sup>−</sup>.  The ratio of the production cross sections, R = σ<sub>ψ(2S)</sub> / σ<sub>J/ψ(1S)</sub>, 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.
%K vector meson, production (INSPIRE)
%K cross section, ratio (INSPIRE)
%K GeV (INSPIRE)
%K psi(3685) (INSPIRE)
%K photoproduction (INSPIRE)
%K DESY HERA Stor (INSPIRE)
%K deep inelastic scattering (INSPIRE)
%K ZEUS (INSPIRE)
%K photon (INSPIRE)
%K kinematics (INSPIRE)
%F PUB:(DE-HGF)25
%9 Preprint
%R 10.3204/PUBDB-2022-03175
%U https://bib-pubdb1.desy.de/record/479627