On the discrepancies in the low energy neutron-deuteron breakup

TL;DR

This paper investigates discrepancies between theoretical predictions and experimental data in neutron-deuteron breakup, focusing on the neutron-neutron quasi-free scattering region, and suggests that an enhanced nn 1S0 force component may resolve the mismatch.

Contribution

It identifies the dominant partial waves affecting QFS cross sections and proposes that strengthening the nn 1S0 interaction could reconcile theory with data.

Findings

QFS cross section is dominated by 1S0 and 3S1-3D1 partial waves.

Standard three-nucleon forces have little effect on QFS discrepancies.

Enhanced nn 1S0 force may resolve the nn QFS data mismatch.

Abstract

In view of recent neutron-deuteron (nd) breakup data for neutron-neutron (nn) and neutron-proton (np) quasi-free-scattering (QFS) arrangements and the large discrepancy found between theoretical predictions and measured nn QFS cross sections, we analyze the sensitivity of the QFS cross sections to different partial wave components of the nucleon-nucleon (NN) interaction. We found that the QFS cross section is strongly dominated by the 1S0 and 3S1-3D1 contributions. Because the standard three-nucleon force (3NF) only weakly influence the QFS region, we conjecture, that it must be the nn 1S0 force component which is responsible for the discrepancy in the nn QFS peak. A stronger 1S0 nn force is required to bring theory and data into agreement. Such an increased strength of the nn interaction will, however, not help to explain the nd breakup symmetric-space-star (SST) discrepancy. Further experimental cross-checkings are required.