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arXiv · 1809.03573

$J/\psi$ polarization in the CGC+NRQCD approach

Yan-Qing Ma·Tomasz Stebel·Raju Venugopalan
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Abstract

We compute the $J/\psi$ polarization observables $\lambda_\theta$, $\lambda_\phi$, $\lambda_{\theta\phi}$ in a Color Glass Condensate (CGC) + nonrelativistic QCQ (NRQCD) formalism that includes contributions from both color singlet and color octet intermediate states. Our results are compared to low $p_T$ data on $J/\psi$ polarization from the LHCb and ALICE experiments on proton-proton collisions at center-of-mass energies of $\sqrt{s}=7$ TeV and 8 TeV. Our CGC+NRQCD computation provides a better description of data for $p_T \leq 15$ GeV relative to extant next-to-leading (NLO) calculations within the collinear factorization framework. These results suggest that higher order computations in the CGC+NRQCD framework have the potential to greatly improve the accuracy of extracted values of the NRQCD universal long distance matrix elements.

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Yan-Qing Ma, Tomasz Stebel, Raju Venugopalan. 2018-09-10. $J/\psi$ polarization in the CGC+NRQCD approach. https://doi.org/10.1007/jhep12(2018)057

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