Off-Mass-Shell $\pi$N Scattering and $pp \to pp \pi^0$

Abstract

We adapt the off-shell $\pi$N amplitude of the Tucson-Melbourne three-body force to the half-off-shell amplitude of the pion rescattering contribution to $pp \to pp \pi^0$ near threshold. This {\em pion} rescattering contribution, together with the impulse term, provides a good description of the data when the half-off-shell amplitude is linked to the phenomenological invariant amplitudes obtained from meson factory $\pi$N scattering data.