Electromagnetic couplings in a collective model of the nucleon

We study the electromagnetic properties of the nucleon and its excitations in a collective model. In the ensuing algebraic treatment all results for helicity amplitudes and form factors can be derived in closed form in the limit of a large model space. We discuss nucleon form factors and transverse electromagnetic couplings in photo- and electroproduction, including transition form factors that can be measured at new electron facilities.Comment: latex, 12 pages, 5 figures uuencoded. Invited talk at the XVIII Nuclear Physics Symposium at Oaxtepec, to be published in Revista Mexicana de Fisic

Algebraic model of baryon structure

We discuss properties of baryon resonances belonging to the Nucleon, Delta, Sigma, Lambda, Xi and Omega families in a collective string-like model for the nucleon, in which the radial excitations are interpreted as rotations and vibrations of the string configuration. We find good overall agreement with the available data. The main discrepancies are found for low lying S-wave states, in particular N(1535), N(1650), Sigma(1750), Lambda*(1405), Lambda(1670) and Lambda(1800).Comment: 6 pages, 2 tables, invited talk Bologna 2000: Structure of the Nucleus at the Dawn of the Centur