A new picture is given of generalized parton distributions probed in experiments in which the probe scale $Q^{ 2}$ and the momentum transfer $\DD^{ 2}$ are well separated. Application of this picture to the $Q^{ 2}$ dependence of the form factors $F_{ 1}, F_{ 2}$ shows that gauge invariant quark orbital angular momentum can be measured and indeed { \it localized} in the transverse profile of the proton. A previous prediction that $\sqrt{ Q^{ 2}}F_{ 2}(Q^{ 2})/F_{ 1}(Q^{ 2}) \sim const. $ is generalized to GPD language. This prediction appears to have been confirmed by recent CEBAF data.
Categories: hep-ph nucl-th