The proton is a composite object, consisting of quarks and gluons, that possesses an intrinsic angular momentum, or spin. As a fundamental quantum mechanical property, spin profoundly influences the proton’s physical characteristics, including its optical, electrical, and magnetic properties. Despite its importance, determining precisely how the constituent particles contribute to the proton's total spin—the proton spin puzzle—remains an unresolved challenge in quantum chromodynamics. In this colloquium, I will summarize the progress made in mapping the spin structure of the proton through experiments at the Relativistic Heavy Ion Collider (RHIC). I will then discuss the exciting prospects for achieving a full resolution to this puzzle using the future Electron-Ion Collider (EIC).
Dr. Kenneth Barish is a Professor of Physics at the University of California, Riverside (UCR). He currently serves as Chair of STAR Experiment's Collaboration Council and has previously served as a STAR Deputy Spokesperson and as a convenor of the Electron-Ion Collider User Group's Yellow-Report Detector Working Group. His UCR service includes his current role as Chair of the UCR Academic Senate, and he was previously chair of the Department of Physics & Astronomy. He received his professional preparation at UC Santa Cruz (BA) and Yale University (MS, M.Phil, PhD), and completed a postdoctoral fellowship at UCLA.