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Charmonium Production via Fragmentation at Higher Orders in alpha_s

P. Ernstrom·P. Hoyer·M. Vanttinen
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Abstract

Quarkonium production at a given large p_T is dominated by parton fragmentation: a parton which is produced with transverse momentum p_T/z fragments into a quarkonium state which carries a fraction z of the parton momentum. Since parton production cross sections fall steeply with p_T, 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 eta_c shows that the higher-order process q -> q eta_c in fact dominates the lowest-order process q -> qg eta_c.

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P. Ernstrom, P. Hoyer, M. Vanttinen. 1996-01-25. Charmonium Production via Fragmentation at Higher Orders in alpha_s. https://arxiv.org/abs/hep-ph/9601333

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