Neutron-proton analyzing power at 12 MeV and inconsistencies in parametrizations of nucleon-nucleon data

TL;DR

This paper provides the most accurate neutron-proton analyzing power data at 12 MeV, revealing significant deviations from existing models and discussing implications for the pion-nucleon coupling constant.

Contribution

It offers a comprehensive and corrected data set for neutron-proton analyzing power at 12 MeV, highlighting discrepancies with current phase-shift analyses and potential models.

Findings

New data deviates from phase-shift analysis predictions

Data impacts the understanding of pion-nucleon coupling constant

Corrected for multiple scattering effects

Abstract

We present the most accurate and complete data set for the analyzing power Ay(theta) in neutron-proton scattering. The experimental data were corrected for the effects of multiple scattering, both in the center detector and in the neutron detectors. The final data at En = 12.0 MeV deviate considerably from the predictions of nucleon-nucleon phase-shift analyses and potential models. The impact of the new data on the value of the charged pion-nucleon coupling constant is discussed in a model study.