  We study the transition of a heavy quark pair from octet to singlet color
configurations at next-to-next-to-leading order (NNLO) in heavy quarkonium
production. We show that the infrared singularities in this process are
consistent with NRQCD factorization to all orders in the heavy quark relative
velocity v. This factorization requires the gauge-completed matrix elements
that we introduced previously to prove NNLO factorization to order v ^2.

High Energy Physics - Phenomenology;High Energy Physics - Theory;Nuclear Theory