Calculation of the s-wave final-state interactions in the Nππ system

The coupled integral equations for the Nππ system are considered for s-wave isobars in S states. For phenomenological objectives the equations are made tractable and the subenergy dependence of the isobar amplitudes is organized according to a collection of resolvents. These quantities satisfy coupled integral equations which are solved by means of a basis-function method. Calculations of the resolvents as functions of the subenergy variable are made for total energy W=1.3, 1.4, and 1.5 GeV. All of the large number of results admit a useful physical parametrization in terms of a sort of complex scattering length. A remarkable sign regularity among the parameters is observed and interpreted