Calculations of Three-Nucleon Reactions

Faddeev calculations using the chiral three-nucleon force in next-to-next-to-next-to-leading-order show that this force is too weak to provide an explanation for the low-energy A (y) puzzle. The large discrepancy between data and theory for the neutron-neutron quasi-free-scattering cross section in low energy neutron-deuteron breakup requires a modification of the neutron-neutron force. We discuss the consequences that a bound state of two neutrons has on neutron-deuteron scattering observables. At higher energies we compare the solutions of the non-relativistic three-nucleon Faddeev equations with three-nucleon force included to the solutions of its Poincar, invariant version.