1996/01/25 by P. Ernstrom, P. Hoyer, M. Vanttinen
Physics and Astronomy · #hep-ph
published as Z.Phys. C73 (1996) 119-124 · 14 pages, LaTeX, 6 Postscript figures, uses epsf.sty
arxiv created 1996/01/25 · arxiv updated 2009/11/30
Quarkonium production at a given large pT is dominated by parton fragmentation: a parton which is produced with transverse momentum pT/z fragments into a quarkonium state which carries a fraction z of the parton momentum. Since parton production cross sections fall steeply with pT, high z fragmentation is favored. However, quantum number constraints may require the emission of gluons in the fragmentation process, and this softens the z dependence of the fragmentation function. We discuss the possibility that higher- order processes may enhance the large z part of fragmentation functions and thus contribute significantly to the quarkonium cross section. An explicit calculation of light quark fragmentation into etac shows that the higher-order process q -> q etac in fact dominates the lowest-order process q -> qg etac.