This award will enable Dr. Alan Picklesimer and Dr. Ruprecht Machleidt, Los Alamos National Laboratory, to collaborate with Dr. Rolf Brockmann, University of Mainz, Federal Republic of Germany. They will study polarized nucleon electroproduction from nuclei at energies and momentum transfers appropriate to the facilities at Mainz, Massachusetts Institute of Technology (The Bates Laboratory), and the Continuous Electron Beam Accelerator Facility under construction at Newport News, Virginia. A major goal of the program, of which this project is a part, is the development of a consistent and complete framework for exploring nuclear structure by looking for relativistic effects and subhadronic degrees of freedom using (e,e'p) reactions initiated by polarized electrons in which the momentum and polarization of the outgoing proton are measured. The research will address a number of issues, including the validity of current conservation in the presence of a nucleon-nucleon interaction derived from meson exchange, the proper inclusion of relativistic wave functions with non-negligible negative energy components, and the consideration of many-body effects. The second part of the program will investigate possible modifications of the Coulomb sum rule, for which experimental evidence has prompted a number of explanations ranging from relativistic effects to modifications of the size of the proton in a medium (i.e. the nucleus). The collaboration will benefit from the expertise of the researchers on nucleon-nucleon interactions, relativistic nuclear physics, and nuclear scattering theory. The researchers have successfully collaborated in the past and this award will allow them to continue their productive work.
