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Study of inclusive J/ψ production in two-photon collisions at LEP II with the DELPHI detector.

Research output: Contribution to Journal/MagazineJournal articlepeer-review

Published
  • . DELPHI Collaboration
  • J. Abdallah
  • A. Sopczak
  • G. , et al. Borrisov
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<mark>Journal publication date</mark>17/07/2003
<mark>Journal</mark>Physics Letters B
Volume565
Number of pages11
Pages (from-to)76-86
Publication StatusPublished
<mark>Original language</mark>English

Abstract

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.