p p -> J/psi+Upsilon+X as a clean probe to the quarkonium production mechanism

TL;DR

This paper proposes that the production of J/psi and Upsilon in proton-proton collisions at the LHC can serve as a clean test for the color-octet mechanism in quarkonium production, with measurable event rates.

Contribution

It identifies a specific process sensitive to poorly known nonperturbative matrix elements, offering a new way to test and constrain quarkonium production models.

Findings

Approximately 1900 events expected at the LHC with 100 fb^{-1} luminosity.

Measurement can provide constraints on the color-octet matrix elements.

Potential to resolve the J/psi polarization puzzle at Fermilab.

Abstract

We report that, unlike most inclusive quarkonium-production processes, the production rate for p p -> J/psi+Upsilon+X dominantly depends on two not well-known long-distance nonrelativistic QCD matrix elements, <O_8^{J/psi}(^3S_1)> and <O_8^{Upsilon}(^3S_1)> at leading order in the strong coupling constant, which account for the transition probabilities of the color-octet spin-triplet heavy-quark-antiquark pairs c\bar{c}_8(^3S_1) -> J/psi and b\bar{b}_8(^3S_1) -> Upsilon, respectively. With the integrated luminosity ~ 100 fb^{-1} at the center-of-momentum energy sqrt{s}=14 TeV we expect that approximately 1900 p p -> J/psi+Upsilon+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/psi 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.