Three-neutron Bound and Continuum States

The three-neutron (3n) system is studied by numerical calculations with the Faddeev three-body formalism for a realistic nucleon-nucleon (NN) potential. A response function for the transition from H-3 to 3n continuum states by an isospin excitation operator is calculated, from which no evidence of 3n resonance state is found. Different methods to extrapolate the 3n energy from bound state energies with an extra attractive effect to the NN potential are examined. While extrapolations with attractive effects by enhanced NN potentials or three-body potentials result in the nonexistence of 3n resonance states, one by external trapping potentials leads to a positive 3n energy, which may be considered as a resonance state. It is found that this contradiction is due to a general defect of the trapping method.