Abstract
We show that hard-scattering factorization is violated in the production of high- hadrons in hadron-hadron collisions, in the case that the hadrons are back-to-back, so that factorization is to be used. The explicit counterexample that we construct is for the single-spin asymmetry with one beam transversely polarized. The Sivers function needed here has particular sensitivity to the Wilson lines in the parton densities. We use a greatly simplified model theory to make the breakdown of factorization easy to check explicitly. But the counterexample implies that standard arguments for factorization fail not just for the single-spin asymmetry but for the unpolarized cross section for back-to-back hadron production in QCD in hadron-hadron collisions. This is unlike corresponding cases in annihilation, Drell-Yan, and deeply inelastic scattering. Moreover, the result endangers factorization for more general hadroproduction processes.
2 More- Received 15 May 2007
DOI:https://doi.org/10.1103/PhysRevD.75.114014
©2007 American Physical Society