par Abdallah, Jalal Mohamad J.;Wickens, John H. 
;Alderweireld, Thomas;Bertrand, Daniel ;D'Hondt, Jorgen;De Clercq, Catherine;Lemonne, Jacques ;Van Lysebetten, Ann;Van Remortel, Nick;Verbeure, F; [et al.]
Référence Physics letters. Section B, 565, 1-4, page (76-86)
Publication Publié, 2003-07
;Alderweireld, Thomas;Bertrand, Daniel ;D'Hondt, Jorgen;De Clercq, Catherine;Lemonne, Jacques ;Van Lysebetten, Ann;Van Remortel, Nick;Verbeure, F; [et al.]Référence Physics letters. Section B, 565, 1-4, page (76-86)
Publication Publié, 2003-07
Article révisé par les pairs
| Résumé : | Inclusive J/ψ production in photon-photon collisions has been observed at LEP II beam energies. A clear signal from the reaction γγ → J/ψ + X is seen. The number of observed N(J/ψ → μ+μ-) events is 36 ± 7 for an integrated luminosity of 617 pb-1, yielding a cross-section of σ(J/ψ + X) = 45 ± 9(stat) ± 17(syst) pb. Based on a study of the event shapes of different types of γγprocesses in the PYTHIA program, we conclude that (74 ± 22)% of the observed J/ψ events are due to 'resolved' photons, the dominant contribution of which is most probably due to the gluon content of the photon. © 2003 Published by Elsevier B.V. |
