2003/06/09 by The DELPHI Collaboration, J. Abdallah, P. Abreu +98 · 5 citations
Physics and Astronomy · #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #hep-ex
paper · pdf · doi:10.1016/s0370-2693(03)00660-9
published as Phys.Lett.B565:76-86,2003 · 13 pages, 8 figures, Accepted by Phys. Lett. B
openalex publication_date 2003/06/09 · arxiv created 2003/07/17 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/04
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 γγ processes 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.