As a clean probe pp → J/ψ+Y+X as a clean probe to the quarkonium production mechanism

We report that, unlike most inclusive quarkonium-production processes, the production rate for pp→J/ψ+Υ+X dominantly depends on two not well-known long-distance nonrelativistic QCD matrix elements, O8J/ψ(S13) and O8Υ(S13) at leading order in the strong coupling constant, which account for the transition probabilities of the color-octet spin-triplet heavy-quark-antiquark pairs cc _̄8(S13)→J/ψ and bb _̄8(S13)→Υ, respectively. With the integrated luminosity ∼100fb ^-1 at the center-of-momentum energy √s=14TeV we expect that approximately 1900 pp→J/ψ+Υ+X events can be observed at the CERN Large Hadron Collider by tagging muon pairs, which are enough to probe to the color-octet mechanism. The forthcoming measurement may provide a useful constraint to resolve the decade-old puzzle for the polarization of prompt J/ψ at the Fermilab Tevatron. If corresponding measured rate is significantly less than the prediction, it may imply that the current values for the color-octet matrix elements are overestimated.