Spin-Flip Interactions and the Puzzle of psi's Polarization at Tevatron

Abstract

Nonrelativistic QCD provides a systematic approach for inclusive decays and productions of a quarkonium. By taking color-octet components into account, the approach can explain the ${\psi }^{\prime }$-anomaly at Tevatron, where the measured production rate at large transverse momentum $p_{\perp }$ is in order of magnitude larger than the predicted with color-singlet components only. With the approach one can predict that the produced $J/\psi$ and ${\psi }^{\prime }$ at large $p_{\perp }$ will be transversely polarized. But the prediction fails in confronting with experimental measurements and this generates a puzzle. We examine the role of spin-flip interactions in the spin density matrix of the transition of a color-octet charm quark pair into $J/\psi$ and ${\psi }^{\prime }$. These interactions will introduce new nonperturbative parameters in the spin density matrix. Our result shows that the impact of the interactions is always to dilute the polarization and can be very significant. Taking the impact into account, predictions for the polarization are more close to the measured than the previous predicted. The same can also be expected for the polarization of $J/\psi$.

arXiv commentmatch the published version Phys.Lett.B645:180-184,2007

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Cited by in corpus (7)

• Color-singlet relativistic correction to inclusive $J/\psi$ production associated with light hadrons at $B$ factories
• Relativistic Correction to Color Octet J/psi Production at Hadron Colliders
• Photoproduction of the heavy quarkonium at the ILC
• Heavy Quarkonium Production through the Semi-Exclusive $e^{+}{e}^{-}$ Annihilation Channels around the $Z^0$ Peak
• Unraveling Gluon Jet Quenching through $J/\psi$ Production in Heavy-Ion Collisions
• Dominant Spin-Flip Effects for the Hadronic Produced $J/\psi$ Polarization at TEVATRON
• Understanding the $e^{+}{e}^{-}\to D^{(\ast )+}{D}^{(\ast )-}$ processes observed by Belle