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

The polarization of prompt J/psi, at the Fermilab Tevatron is calculated within the nonrelativistic QCD factorization framework. The contribution from radiative decays of P-wave charmonium states decreases, but does not eliminate, 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 prediction is consistent with measurements by the CDF Collaboration at intermediate values of p(T), but disagrees by about 3 standard deviations at the largest values of p(T) measured.