Photo-production of psi(2S) mesons at HERA

Quasi-elastic (z > 0.95) photo-production of ψ(2S) mesons has been observed at HERA for photon-proton centre-of-mass energies in the range 40 to 160 GeV. The ψ(2S) mesons were identified through their decays to ℓ+ℓ- and to J/ψπ+π-, where the J/ψ subsequently decays to ℓ+ℓ-, the lepton ℓ being...

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Bibliographic Details
Main Authors: Adloff, C, Aid, S, Anderson, M, Andreev, V, Andrieu, B, Arkadov, V, Arndt, C, Ayyaz, I, Babaev, A, Bahr, J, Ban, J, Baranov, P, Barrelet, E, Barschke, R, Bartel, W, Bassler, U, Beck, M, Behrend, H, Beier, C, Belousov, A, Berger, C, Bernardi, G, Bertrand-Coremans, G, Beyer, R, Biddulph, P
Format: Journal article
Language:English
Published: 1998
Description
Summary:Quasi-elastic (z > 0.95) photo-production of ψ(2S) mesons has been observed at HERA for photon-proton centre-of-mass energies in the range 40 to 160 GeV. The ψ(2S) mesons were identified through their decays to ℓ+ℓ- and to J/ψπ+π-, where the J/ψ subsequently decays to ℓ+ℓ-, the lepton ℓ being either a muon or an electron. The cross-section for quasi-elastic photoproduction was measured to be (18.0 ± 2.8(stat) ± 3.0(syst)) nb at a photon-proton centre-of-mass energy of 80 GeV. The ratio of the ψ(2S) to J/ψ quasi-elastic cross-sections is (0.150 ± 0.027(stat) + 0.022(syst)). © 1998 Elsevier Science B.V.