Helicity decomposition for inclusive J/psi production

We present a general method for calculating inclusive cross sections for the production of heavy quarkonium states with definite polarization within the NRQCD factorization approach. Cross sections for polarized production can involve additional matrix elements that do not contribute to cross sections for unpolarized production. They can also include interference terms between parton processes that produce Q (Q) over bar pairs with different total angular momentum. The interference terms cancel upon summing over polarizations. Our method can be generalized to N dimensions and Is, therefore, compatible with the use of dimensional regularization to calculate radiative corrections. We illustrate the method by applying it to the production of J/psi via the parton processes q (q) over bar --> c (c) over bar and gg --> c (c) over bar.