Heavy quarkonium production and polarization

We present a perturbative QCD factorization formalism for the production of heavy quarkonia of large transverse momentum p _T at collider energies, which includes both the leading-power (LP) and next-to-leading-power (NLP) contributions to the cross section in the mQ2/pT2 expansion for heavy quark mass m _Q. We estimate fragmentation functions in the nonrelativistic QCD formalism and reproduce the bulk of the large enhancement found in explicit next-to-leading-order calculations in the color-singlet model. Heavy quarkonia produced from NLP channels prefer longitudinal polarization.