Quarkonium production in an improved color evaporation model

Color and Spin in Quarkonium Production

I describe the NRQCD factorization approach to the inclusive production of heavy quarkonium, contrasting it with the color-singlet and color evaporation models. These approaches differ dramatically in their assumptions about the roles played by color and spin in the production process. They also differ dramatically in their predictions for the production of charmonium at large transverse momentum.

Signatures of Color-octet Quarkonium Production A

I briefly review the nonrelativistic QCD picture of quarkonium production and its confrontation with experiment in various production processes.

Quantitative Tests of Color Evaporation: Charmonium Production

The color evaporation model simply states that charmonium production is described by the same dynamics as DD̄ production, i.e., by the formation of a colored cc̄ pair. Its color happens to be bleached by soft final-state interactions. We show that the model gives a complete picture of charmonium production including low-energy production by proton, photon and antiproton beams, and high-energy pro...

The Soft Gluon Emission Process in the Color-Octet Model for Heavy Quarkonium Production

The Color-Octet Model has been used successfully to analyze many problems in heavy quarkonium production. We examine some of the conceptual and practical problems of the soft gluon emission process in the Color-Octet Model. We use a potential model to describe the initial and final states in the soft gluon emission process, as the emission occurs at a late stage after the production of the heav...

Quarkonium Production