NSTAR 2001 - PROCEEDINGS OF THE WORKSHOP ON THE PHYSICS OF EXCITED NUCLEONS

The study of N∗s can provide us with critical insights into the nature of QCD in the confinement domain. The keys to progress in this domain are the identification of its important degrees of freedom and the effective forces between them. The nucleon is the simplest system in which the nonabelian character of QCD is manifest. There are Nc quarks in a baryon because there are Nc colors, and as a consequence Gell-Mann and Zweig were forced to introduce the quarks in order to describe the octet and decuplet baryons.This volume gives a status report on the recent experimental and theoretical results in the field of nucleon resonance physics. A wealth of new high precision data was presented from facilities around the world, such as BES, BNL, ELSA, GRAAL, JLab, MAMI, MIT/Bates, SPring8, and Yerevan. Particular emphasis was laid on polarization degrees of freedom and large acceptance detectors as precision tools for studying small but important transition amplitudes, and the helicity (spin) structure of the nucleon. There were new results describing the nucleon resonance structure on the basis of quantum chromodynamics, either directly in terms of quarks and gluons by means of lattice gauge theory, or in terms of hadrons in the framework of chiral field theories. A status report on duality showed the surprising connections between the physics of the low energy nucleon resonance region and the realm of quark structure functions in deep inelastic scattering. Finally, this volume contains a summary report of the BRAG workshop, devoted to the analysis of baryon resonances.

Table of Contents:
Nucleon Resonances in the Quark Model (S Capstick); Recent Developments in the Dynamical and Unitary Isobar Models for Pion Electromagnetic Production (S N Yang et al.); The Role of the Pion in Nucleon Resonance Structure (D-O Riska); Generalized Polarizabilities in a Constituent Quark Model (S Scherer et al.); Multipole Analysis for Pion Photoproduction with MAID and a Dynamical Model (S S Kamalov et al.); Electroweak Properties of Baryons in a Covariant Chiral Quark Model (S Boffi); Neutron Charge Form Factor and Quadrupole Deformation of the Nucleon (A J Buchmann); Vector Meson Photoproduction in the Quark Model (Q Zhao); The New Crystal Ball Experimental Program (W J Briscoe); Lattice Study of Nucleon Properties with Domain Wall Fermions (S Sasaki); and other papers.