Asymmetric di-jet production in polarized hadronic collisions

Using the collinear QCD factorization approach, we study the single-transverse-spin dependent cross section Delta sigma(S-perpendicular to) for the hadronic production of two jets of momenta P, = P + q/2 and P-2 = -P + q/2. We consider the kinematic region where the transverse components of the momentum vectors satisfy P-perpendicular to >> q(perpendicular to) >> Delta QCD. For the case of initial-state gluon radiation, we show that at the leading power in q(perpendicular to)/P-perpendicular to and at the lowest non-trivial perturbative order, the dependence of Delta sigma(S-perpendicular to) on q(perpendicular to) decouples from that on P-perpendicular to, so that the cross section can be factorized into a hard part that is a function only of the single scale P-perpendicular to, and into perturbatively generated transverse-momentum dependent (TMD) parton distributions with transverse momenta kappa(perpendicular to) = O(q(perpendicular to)). (c) 2007 Elsevier B.V. All rights reserved.