  The production of J/Psi mesons in photon photon collisions allows for a test
of factorization in color-octet processes as predicted by NRQCD and observed at
the Tevatron. We calculate the cross sections for J/Psi production with direct
and resolved photons, including also the feed-down from chi_{cJ} and Psi'
decays. Our NRQCD predictions are nicely confirmed by recent data from the
DELPHI collaboration at CERN LEP2.

High Energy Physics - Phenomenology