MEDIUM-ENERGY N-PI-PI-DYNAMICS .2. RESCATTERING CORRECTIONS TO THE ISOBAR MODEL

A new parametrization of the isobar-model type is proposed for Nππ final states. It incorporates the major subenergy-dependent variations induced by unitarity (rescattering) corrections to the conventional nonunitary isobar model. These corrections have been calculated in JP waves 12+, 12-, 32+, and 32- using the dynamical theory based on subenergy unitarity and analyticity recently developed by the authors. All the corrections vary relatively smoothly with subenergy. It is argued that this result implies that the conclusions of the existing nonunitary fits will not be seriously modified by the inclusion of the rescattering corrections. There are, however, some significant subenergy variations. In all the important cases the detailed results exhibit one of two distinctive subenergy effects, which are interpreted physically; each effect occurs in a systematic fashion and can be succinctly parametrized. Some of the variations may be detectable with improved statistics. © 1979 The American Physical Society.