Comprehensive description of $J/\psi$ production in proton-proton collisions at collider energies

Abstract

We employ a small $x$ Color Glass Condensate (CGC)+ Non-Relativistic QCD (NRQCD) formalism to compute $J/\psi$ production at low $p_{\perp }$ in proton-proton collisions at collider energies. Very good agreement is obtained for total cross-sections, rapidity distributions and low momentum $p_{\perp }$ distributions. Similar agreement is obtained for ${\psi }^{\prime }$ production. We observe an overlap region in $p_{\perp }$ where our results match smoothly to those obtained in a next-to-leading order (NLO) collinearly factorized NRQCD formalism. The relative contribution of color singlet and color octet contributions can be quantified in the CGC+NRQCD framework, with the former contributing approximately $10\%$ of the total cross-section.

Comments: 6 pages, 3 figures, typos corrected, final version accepted by Physical Review Letters