Gluon recombination in high parton density QCD: inclusive pion production

We argue that the collinear factorization of the fragmentation functions in high energy hadron and nuclei collisions breaks down at transverse momenta kT (le) Qs/g due to high parton densities in the colliding hadrons and/or nuclei. We calculate, at next-to-leading order in projectile parton density and to all orders in target parton density, the double-inclusive cross-section for production of a pair of gluons in the scalar JPC = 0++ channel. Using the low energy theorems of QCD we find the inclusive cross-section for π-meson production.