Nuclear Physics Seminar

We argue that the collinear factorization of the fragmentation functions in high energy hadron and nuclear collisions breaks down at transverse momenta k_T ~ Q_s/g due to high parton densities in the colliding hadrons and/or nuclei. We then argue that gluon recombination, which is basically the merging of two classical fields, should dominate in that k_T regime. 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 J^{PC} = 0^{++} channel. We then generalize our results to AuAu collisions at RHIC energy. Using the low energy theorems of QCD we find the inclusive cross-section for pion meson and baryon production. Finally, we compare our results for baryon to meson ratio with the experimental data from RHIC.