Double quarkonium production at the LHC

Within the framework of nonrelativistic QCD factorization (NRQCD) approach, we investigate inclusive productions of two spin-triplet S-wave quarkonia at the Large Hadron Collider. The total cross sections for pp → 2J/ψ + X, pp → 2ϒ + X, and pp → J/ψ + ϒ + X integrated over the rapidity range |y| ≤ 2.4 are 35 nb, 49 pb, and 13 pb at the center-of-momentum energy √s = 14 TeV, respectively. We find that the color-singlet channels dominate over the color-octet channels in the pp → 2J/ψ + X and pp → 2ϒ + X processes, while the color-octet channels may be enhanced at large transverse momentum. We find that in the pp → J/ψ + ϒ + X process, the color-singlet channel is much suppressed compared to the color-octet channel at leading order in the strong coupling α_s, especially, at large transverse momentum. Therefore, the pp → J/ψ + ϒ + X process may provide a good probe to the color-octet mechanism or give a stringent bound on the color-octet matrix elements.