Study of Inclusive J= Production in Two-Photon Collisions at LEP II with the DELPHI Detector

Inclusive J= production in photon-photon collisions has been observed by the DELPHI collaboration at LEP II beam energies. A clean signal from the reaction ! J= + X is seen. The number of observed events N(J= ! + ) is 36 7 for the integrated luminosity of 617 pb 1 , yielding a cross section of (J= + X) = 45:3 18:8 pb. Based on a study of the event shapes of dierent types of processes in the PYTHIA program, we conclude that (74 22)% of the observed J= events are due to the ‘resolved’ photons, the dominant contribution of which is likely due to gluon content of the photon. The second important contribution stems from vector-dominance process.