The Form Factors of the Proton

College Of William And Mary, Williamsburg VA

Investigators

Abstract

Two experiments at Jefferson Laboratory (JLab) in 1998 and 2000 have shown that the ratio of proton electric and magnetic form factors decreases sharply with momentum transfer, in definite disagreement with the results obtained by the standard "Rosenbluth separation" technique. The JLab experiments measured the polarization transfer from projectile to target in elastic ep scattering, rather than cross section. The current project will continue these investigations to the highest momentum transfer possible with the 6 GeV JLab accelerator. The findings from the first two experiments have definitively changed the way physicists understand the structure of the proton, and have directly challenged theoretical models of the proton. Among numerous theoretical work generated by our JLab results, we note that efforts to solve the theory of quantum chromodynamics (QCD) in the non-perturbative domain are beginning to have predictive power in the domain investigated by these experiments. The experiments described in this proposal involve a large collaboration from faculty members at universities, with their postdoctoral associates, and graduate and undergraduate students. These students are diverse in origin and culture, and will receive exceptional training at a technologically advanced facility, JLab. Each summer 6-8 physics undergraduates join the effort and get hands-on practical training. This project support one WM graduate student and one of the two postdoctoral fellows associated with the core group. ---