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arXiv · 0911.2113

Polarization of prompt J/psi in proton-proton collisions at RHIC

Hee Sok Chung·Seyong Kim·Jungil Lee·Chaehyun Yu
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Abstract

Within the framework of the nonrelativistic QCD (NRQCD) factorization approach, we compute the polarization of prompt J/psi produced at the Brookhaven's Relativistic Heavy-Ion Collider from proton-proton collisions at the center-of-momentum energy sqrt{s}=200 GeV. The perturbative contributions are computed at leading order in the strong coupling constant. The prediction reveals that the color-singlet contribution severely underestimates the PHENIX preliminary data for the differential cross section integrated over the rapidity range |y|<0.35 and its contribution is strongly transversely polarized, which disagrees with the PHENIX preliminary data. After including the color-octet contributions, we find that the NRQCD predictions for both the cross section and polarization over the transverse-momentum range 1.5 GeV < p_T < 5 GeV (1.5 GeV < p_T < 2 GeV) integrated over the rapidity range |y|<0.35 (1.2 < |y| < 2.2) agree with the data within errors.

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Hee Sok Chung, Seyong Kim, Jungil Lee, Chaehyun Yu. 2009-11-11. Polarization of prompt J/psi in proton-proton collisions at RHIC. https://doi.org/10.1103/physrevd.81.014020

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