PHOTOPRODUCTION AND ELECTROPRODUCTION OF N-STAR IN A QUARK-MODEL

We review and update the theory on photo- and electroproduction in the nonrelativistic constituent quark model (NRCQM). The electromagnetic interaction Hamiltonian for a three-quark system is discussed, particularly the nonadditive term and the role of the binding potential which have been neglected in previous calculations. We find that the successes of the NRCQM survive these relativistic corrections and make predictions for baryon-resonance excitation that can be tested in forth-coming experiments; however, we suggest that some QCD improvements to the NRCQM are incomplete. Finally we discuss the limits of application of the long-wavelength approximation in resonance photo- and electroproduction. © 1990 The American Physical Society.