Transverse single spin asymmetries in hadronic gauge boson production

Measuring the sign of the Sivers asymmetry in the Drell-Yan process is one of the most important projects for high-energy spin physics. Such a measurement not only would critically test our current understanding of transverse single spin asymmetries in the framework of QCD, but has also far-reaching consequences beyond spin physics. Based on new studies we argue that the same underlying dynamics can be tested in the production of W-bosons in proton-proton collisions. Numerical studies for kinematics at the RHIC will be shown. Moreover, we present results for another spin correlation in the Drell-Yan process which is also complementary to the Sivers effect, but does not rely on the factorization in terms of transverse momentum dependent correlators.