POETIC IV

Abstract: Abhay Deshpande

Physics and the Status of the EIC Project in the US

No one doubts that Quantum Chromodynamics (QCD) is the correct theory for Strong Interactions, but our understanding of it remains incomplete. For example, how different are the parton distribution functions in nuclei compared to those in nucleons, especially at high energies? Of particular interest is behavior of the gluon distributions at extremely high energy where some of the most interesting predictions have been made. What role do gluons play in determining the spin of the proton and the neutron? Do the partons dynamically contribute to the nucleon's spin as well? Do the partons carry angular momentum? What is their confined transverse motion inside the nucleon? None of these questions yet have satisfactory quantitative answers. Data collected in the last two decades at BNL, CERN, DESY and Jefferson Laboratory, both with polarized and unpolarized collisions, over a wide range in center of mass energy and beam species have underlined this fact. I will review the case for the future Electron Ion Collider (EIC) in this context. I will give a brief update on the status of the project in the US, including the machine designs for (1) the EIC at BNL using the existing RHIC (eRHIC) and (2) the one at Jefferson Lab using the 12 GeV CEBAF presently under construction (MEIC). Towards the end I will comment on the possible timeline and the milestones to pass towards the realization of EIC through the NSAC's Long Range Planning process.