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

TL;DR

This paper explores how a narrow resonance observed in double-pionic fusion reactions impacts elastic neutron-proton scattering, predicting observable effects that could confirm its existence and nature.

Contribution

It introduces the implications of a newly observed resonance structure on neutron-proton scattering observables and proposes experimental signatures for its verification.

Findings

Resonance could significantly influence total cross section data.

Predicted energy dependence in analyzing power offers a test for the resonance.

Inclusion of the resonance improves data description.

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.