QCD SELECTION-RULES IN POLARIZED HADRON-COLLISIONS

Plans are underway to measure spin asymmetries at large momentum trans fer in hadron hadron collisions at RHIC and elsewhere. Proposals have focused on measuring quark transversity and quark and gluon helicity d istributions in the nucleon. These experiments will also provide a str ong and simple test of perturbative QCD, namely that A(TT)/A(LL) << 1 in pp --> 2 jets + X and several related processes, whereas A(TT)/A(LL ) similar to 1 in Drell-Yan production of muon pairs. The prediction t ests the helicity, twist and chirality selection rules of perturbative QCD that form the foundation for the analysis of spin dependent hard processes. We estimate the ratio A(TT)/A(LL) numerically for polarized protons at RHIC.