Inclusive double-quarkonium production at the Large Hadron Collider

Abstract

Based on the nonrelativistic QCD (NRQCD) factorization formalism, we investigate inclusive productions of two spin-triplet S-wave quarkonia pp → 2J/ψ + X, 2Υ + X, and J/ψ + Υ + X at the CERN Large Hadron Collider. The total production rates integrated over the rapidity (y) and transverse-momentum (p T ) ranges |y| < 2.4 and p T < 50GeV are predicted to be σ[pp → 2J/ψ + X] = 22 (35) nb, σ[pp → 2Υ + X ]= 24 (49) pb, and σ[pp → J/ψ + Υ + X ] = 7 (13) pb at the center-of-momentum energy $ \sqrt {s} = 7\left( {14} \right)\;{\text{TeV}} $ . In order to provide predictions that can be useful in both small- and large-p T regions, we do not employ the fragmentation approximation and we include the spin-triplet S-wave color-singlet and color-octet channels for each quarkonium final state at leading order in the strong coupling. The p T distributions of pp → 2J/ψ + X and 2Υ + X in the low-p T region are dominated by the color-singlet contributions. At leading order in the strong coupling, the color-singlet channel is absent for pp → J/ψ + Υ + X. Therefore, the process pp → J/ψ + Υ + X may provide a useful probe to the color-octet mechanism of NRQCD.