J/\psi Production in Direct and Resolved Photon Collisions

Abstract

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.

Comments: Talk presented at the QCD Moriond 2003 conference. 4 pages, 3 postscript figures