PHENIX Spin Physics Overview

Understanding the spin structure of the proton is of large interest to the nuclear physics community and it is one of the main goals of the spin physics program at the Relativistic Heavy Ion Collider (RHIC). Measurements from data taken by the PHENIX detector with transverse (p ↑ + p, p ↑ + Al, p ↑ + Au) and longitudinal (⃗p + ⃗p) proton polarization play an important role in this, in particular due to the leading order access to gluons in polarized protons. This is a crucially important counterpart to measurements made in lepton-hadron scattering experiments where gluons are not accessible at leading order. Transverse spin asymmetries provide insight into initial and final-state spinmomentum and spin-spin parton-hadron correlations, while longitudinal spin asymmetries provide access to parton polarization. A number of important recent PHENIX results and ongoing analyses will be presented, along with a discussion of how these measurements contribute to our understanding of proton spin structure.