Width of πNN resonances near threshold

We use an isobar model and first-order perturbation theory to determine the width of resonances that decay into a pion and two nucleons near the πNN threshold. The perturbation is given in this case by the three-body unitarity cuts. As an application we study the case of the d' resonance observed in pionic double-charge-exchange reactions on nuclei. We consider the possible isospin assignments of this resonance and conclude that the isospin 2 assignment is the correct one.