Electromagnetic multipoles - theory issues

Abstract

Some predictions of the Hypercentral Constituent Quark Model for the helicity amplitudes are discussed and compared with data and with the recent analysis of the Mainz group; the role of the pion cloud contribution in explaining the major part of the missing strength at low $Q^2$ is emphasized.

Comments: Physics of excited nucleons (J.-P. Bocquet, V. Kuznetsov, D. Rebreyend eds.), World Scientific, Singapore 2004, 377-381 BRAG Meeting, Grenoble 23 March 2004