Probing ud asymmetry in the proton via W and Z production

The sensitivity of W and Z production at RHIC to the possible ud asymmetry in the proton is studied. The ratios of the W+ over W− production cross sections in p + p collision, as well as the ratios of the W+ and Z production cross sections for p + p over p + d collisions, are shown to be sensitive to this asymmetry. Predictions of various theoretical models for these ratios are presented.