Physics Opportunities at the Future eRHIC Electron-Ion Collider

The 2015 nuclear physics long-range plan endorsed the realization of an electron-ion collider as the next large construc- tion project in the United States. This new collider will provide definite answers to the following questions: How are the sea quarks and gluons, and their spins, distributed in space and momentum inside the nucleon? How are these quark and gluon distributions correlated with overall nucleon properties, such as spin direction? What is the role of the orbital motion of sea quarks and gluons in building up the nucleon spin? The eRHIC project is the Brookhaven National Laboratory’s vision for the realization of the future electron-ion collider. eRHIC, with its high luminosity ( > 10 33 cm − 2 s − 1 ), wide kinematic reach in center-of-mass-energy (45 GeV to 145 GeV) since day-1 and highly polarized nucleon ( P ≈ 70%) and electron ( P ≈ 80%) beams provides an unprecedented opportunity to reach new frontiers in our understanding of the internal dynamic structure of nucleons. We give a brief description of the eRHIC project and highlight several key high precision measurements from the planned broad physics program at the future electron-ion collider and the expected impact on our current understanding of the spatial structure of nucleons and nuclei, and the transition from a non-saturated to a saturated state of nuclear matter.