  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.
