Abstract

The polarized antiquark distributions in the proton can be measured by studying spin asymmetries in vector boson production in longitudinally polarized proton–proton collisions. The STAR and PHENIX experiments at BNL RHIC have reported first observations of single spin asymmetries in W± production most recently. We compute the QCD corrections to single and double spin asymmetries, taking account of the leptonic decay of the W± boson and of restrictions on the kinematical acceptance of the detectors. The QCD corrections have only a small impact on the asymmetries, such that a reliable extraction of the polarized antiquark distributions can be envisaged once more precise measurements are made.