Physics Opportunity at the Electron-Ion Collider (EIC)

Abstract: The Electron-Ion Collider (EIC) is a next-generation facility under construction at Brookhaven National Laboratory, uniquely designed to collide polarized electrons with polarized protons and ions. With its high luminosity, broad kinematic reach, and precise control over beam polarizations, the EIC will provide transformative insights into Quantum Chromodynamics (QCD). It will enable three-dimensional imaging of partons inside nucleons, reveal the role of gluons in the nucleon's mass and spin, and probe gluon saturation at small Bjorken-x. Furthermore, the EIC will perform detailed measurements of gluon distributions in nuclei and explore how QCD dynamics evolve in nuclear environments. The ePIC detector, currently under development, is tailored to fully exploit these capabilities through advanced tracking, calorimetry, and particle identification across wide rapidity ranges. The EIC's unique complementarity with heavy-ion programs at RHIC and LHC makes it a central tool for completing the QCD picture of visible matter.