I compute the leading color-octet contributions to the process within the nonrelativistic QCD (NRQCD) factorization formalism. In the color-singlet model, can only be produced when the photon interacts through its structure function, while the color-octet mechanism allows for production of via direct photon-gluon fusion. Resolved photon processes can be distinguished easily from direct photon processes by examining the fraction of the incident photon energy carried away by the in the event. Therefore, this process provides a conclusive test of the color-octet mechanism. production is particularly sensitive to the NRQCD matrix element which figures prominently in the fragmentation production of at large in hadron colliders. I also examine the predictions of the color evaporation model (CEM) of quarkonium production and find that this process can easily discriminate between the NRQCD factorization formalism and the CEM.
- Received 15 November 1996
- Published in the issue dated 1 April 1997
© 1997 The American Physical Society