We employ a small $x$ color glass condensate (CGC)+ nonrelativistic 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 collinearly factorized NRQCD formalism. The relative contribution of color singlet and color octet contributions can be quantified in the $\mathrm{CGC}+\mathrm{NRQCD}$ framework, with the former contributing approximately 10% of the total cross section.

• Received 5 September 2014

DOI:https://doi.org/10.1103/PhysRevLett.113.192301