Transverse-spin physics at RHIC/PHENIX

The PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC) probes the proton's transverse-spin structure by measuring asymmetries in transversely polarized proton(+) proton collisions. The large single-transverse-spin asymmetries observed at high-xF arise from either the Sivers effect, the Collins effect or higher-twist effects. PHENIX aims to disentangle these effects with complementary measurements which provide sensitivity to each effect. This talk summarizes PHENIX's current measurements and a planned upgrade to the experiment to better measure each effect.