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arXiv · 0908.0754

Heavy-Quarkonium Production in High Energy Proton-Proton Collisions at RHIC

Stanley J. Brodsky·Jean-Philippe Lansberg
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Abstract

We update the study of the total Psi and Upsilon production cross section in proton-proton collisions at RHIC energies using the QCD-based Color-Singlet (CS) Model, including next-to-leading order partonic matrix elements. We also include charm-quark initiated processes which appear at leading order in alpha_s, but which have so far been overlooked in such studies. Contrary to earlier claims, we show that the CS yield is consistent with measurements over a broad range of J/Psi rapidities. We also find that charm-quark initiated processes, including both intrinsic and sea-like charm components, typically contribute at least 20% of the direct J/Psi yield, improving the agreement with data both for the integrated cross section and its rapidity dependence. The key signature for such processes is the observation of a charm-quark jet opposite in azimuthal angle phi to the detected J/Psi. Our results have impact on the proper interpretation of heavy-quarkonium production in heavy-ion collisions and its use as a probe for the quark-gluon plasma.

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Stanley J. Brodsky, Jean-Philippe Lansberg. 2009-08-05. Heavy-Quarkonium Production in High Energy Proton-Proton Collisions at RHIC. https://doi.org/10.1103/physrevd.81.051502

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