Higher order QCD corrections to processes with polarized particles

QCD higher order corrections (HOC) to three processes are considered: (i) Direct photon production in longitudinally polarized hadron-hadron collisions with numerical applications to proton-proton collisions; (ii) lepton-pair production in transversely polarized hadron-hadron collisions with numerical applications to proton-proton collisions; (iii) heavy quark pair production by polarized and unpolarized photons. The HOC to all three processes are found to be significant. Processes (i) and (ii) are shown to be sensitive probes of the proton's polarized gluon distribution and the transversity distributions, respectively. The asymmetries are found to exhibit perturbative stability. Process (iii) is considered as a background to $ gamma gamma rightarrow H sp* rightarrow b =b$ (standard model). As well, top-quark production not too far above threshold is considered