Implications of the ABC Resonance Structure on Elastic Neutron-Proton Scattering

Abstract

In recent WASA-at-COSY measurements of the basic double-pionic fusion reactions $pn\to d{\pi }^0{\pi }^0$ and $pn\to d{\pi }^{+}{\pi }^{-}$ a narrow resonance structure with $I(J^P)=0(3^{+})$ in the total cross section has been found. If this constitutes a s-channel resonance in the $pn$ system, then it should cause distinctive consequences in $pn$ scattering. The magnitude of the decay width into the $pn$ channel is estimated and the expected resonance effects in integral and differential $pn$ scattering observables are presented. The inclusion of the resonance improves the description of total cross section data. For the analyzing power a characteristic energy dependence is predicted, which should allow a crucial experimental check of the resonance hypothesis.