Dynamical study of the $\Delta$ excitation on the nucleon and deuteron

T.-S. H. Lee

Physics Division, Argonne National Laboratory, Argonne, Il.60439

I will report on the status of the dynamical model we have developed[1,2] for investigating the pion photo- and electro- productions on the nucleon. The comparisons of our predictions with the most recent data from Jlab will be presented. The differences with other dynamical models will be discussed. We will also present an interpretation of the $\Delta$ parameters of our model in terms of constituent quark model and pion loop corrections. Our model has been applied to predict $d(\gamma,\pi)$ and $d(e,e'\pi)$ reactions, in conjuction with the recent experimental efforts at LEGS and JLab. Some preliminary results will be presented.

1. T. Sato and T.-S. H. Lee, Phys. Rev. C54, 2660 (1996)

2. T. Sato and T.-S. H. Lee, Phys. Rev. C63, 055201 (2001)