On the discrepancies in the low-energy neutron-deuteron breakup

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 S-1(0) and S-3(1)-D-3(1) contributions. Because the standard three-nucleon force (3NF) only weakly influences the QFS region, we conjecture that it must be the nn S-1(0) force component which is responsible for the discrepancy in the nn QFS peak. A stronger S-1(0) 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.