NRQCD colour-octet expansion vs LHC quarkonium production: signs of a hierarchy puzzle?

Abstract

The observation of unpolarized quarkonium production in high energy pp collisions, at mid rapidity, implies a significant violation of the non-relativistic QCD (NRQCD) velocity scaling rules. A precise experimental confirmation of this picture could definitely rule out the current formulation of the factorization expansion. This conclusion relies on current perturbative determinations of the short-distance kinematic factors and may be reverted if improved calculations would modify, in a very specific way, their transverse momentum dependences. That solution would result, however, in a full degeneracy in the presently assumed basis of ${}^{2S+1}{L}_J$ Fock states. Therefore, whatever the outcome, improved polarization measurements will challenge and improve our fundamental understanding of quarkonium production.

To appear in European Physical Journal C

References in corpus (8)

• Quarkonium production in the LHC era: a polarized perspective
• Next-to-leading-order tests of nonrelativistic-QCD factorization with $J/\psi$ yield and polarization
• Measurement of J/psi and psi(2S) prompt double-differential cross sections in pp collisions at sqrt(s) = 7 TeV
• Measurement of $\psi (2S)$ polarisation in $pp$ collisions at $\sqrt{s}=7$ TeV
• Measurement of chi_c1 and chi_c2 production with sqrt(s) = 7 TeV pp collisions at ATLAS
• Measurement of the production cross-section of $\psi (2S)\to J/\psi (\to {\mu }^{+}{\mu }^{-}){\pi }^{+}{\pi }^{-}$ in $pp$ collisions at $\sqrt{s}=7$ TeV at ATLAS
• Measurement of the ${\rm Y}$ polarizations in $pp$ collisions at $\sqrt{s}$=7 and 8TeV
• HELAC-Onia 2.0: an upgraded matrix-element and event generator for heavy quarkonium physics

Cited by in corpus (2)

• From prompt to direct J/$\psi$ production: new insights on the ${\chi }_{c1}$ and ${\chi }_{c2}$ polarizations and feed-down contributions from a global-fit analysis of mid-rapidity LHC data
• Measurement of the polarizations of prompt and non-prompt J/$\psi$ and $\psi$(2S) mesons produced in pp collisions at $\sqrt{s}$ = 13 TeV