Modifications of the Chew-Low theory caused by the inclusion of $\rho$-nucleon intermediate states are examined. Although this effect changes the form factors necessary to reproduce the (3, 3) resonance, no significant change in the resulting phase shifts is obtained. The use of $\rho$-nucleon intermediate states does not eleiminate the "ghost state" pole in those spin-isospin channels for which the driving term is repulsive.

NUCLEAR REACTIONS Scattering theory, Low equation, $\pi$-nucleon scattering.

• Received 16 December 1977

DOI:https://doi.org/10.1103/PhysRevC.18.914