Sidney D. Drell Proton Form Factors


Over the past decade there have been a progression of beautiful experiments on elastic electron proton scattering starting with the work of Hofstadter and collaborators and extending to broad new rang-es of higher energies and momentum transfers in the recently reported results from the Stanford Linear Accelerator Center. From these the proton electromagnetic form factors have been deduced up to momentum transfers of t = q2 25 (GeV/c)2. The original measurements in the very beginning showed that the proton was a rather fat, diffuse charge and current distribution with a root mean square radius of N 0.8f. Nambu first recognized the 0 need for the existence of an isoscalar vector meson resonance, the w , and Frazer and Fulco subsequently showed in detail the case for the isovector p 0 in order to provide a theoretical basis for the form factor behavior. Indeed the early form factor work led to predictions that there existed vector mesons of sub-nucleonic mass, and from this grew the generally very successful vector dominance model. However, as discussed by Wilson in a recent Comments (Vol. 1, NO. 3, May 1967), a p” dominant model for the isovector form factor is inadequate to fit the data accurately-and in particular it fails for the large t behavior which shows the form factor GMp (see Wilson) falling at least as fast as L 1 t2 -. q4 To see this we turn to the canonical

Cite this paper

@inproceedings{Drell1999SidneyDD, title={Sidney D. Drell Proton Form Factors}, author={S. D. Drell}, year={1999} }