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J/Ψproduction, $χ$ polarization and Color Fluctuations

L. Gerland·L. Frankfurt·M. Strikman·H. Stöcker·W. Greiner
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Abstract

The hard contributions to the heavy quarkonium-nucleon cross sections are calculated based on the QCD factorization theorem and the nonrelativistic quarkonium model. We evaluate the nonperturbative part of these cross sections which dominates at $\sqrt{s_{NN}}\approx 20$ GeV at the Cern Super Proton Synchrotron (SPS) and becomes a correction at $\sqrt{s_{NN}}\approx 6$ TeV at the CERN Large Hadron Collider (LHC). $\J$ production at the CERN SPS is well described by hard QCD, when the larger absorption cross sections of the $χ$ states predicted by QCD are taken into account. We predict an $A$-dependent polarization of the $χ$ states. The expansion of small wave packets is discussed.

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L. Gerland, L. Frankfurt, M. Strikman, H. Stöcker, W. Greiner. 1998-07-27. J/Ψproduction, $χ$ polarization and Color Fluctuations. https://doi.org/10.1103/physrevlett.81.762

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