Polarization of prompt J/psi at the Fermilab Tevatron - art. no. 094005

The polarization of prompt J/psi, at the Fermilab Tevatron is calculated wi thin the nonrelativistic QCD factorization framework. The contribution from radiative decays of P-wave charmonium states decreases, but does not elimi nate, the transverse polarization at large transverse momentum. The angular distribution parameter alpha for leptonic decays of the J/psi is predicted to increase from near 0 at p(T)=5 GeV to about 0.5 at p(T)=20 GeV. The pre diction is consistent with measurements by the CDF Collaboration at interme diate values of p(T), but disagrees by about 3 standard deviations at the l argest values of p(T) measured.