Low-momentum nucleon-nucleon interaction and its application to few-nucleon systems

Low-momentum nucleon-nucleon interactions are derived within the framework of a unitary-transformation theory, starting with realistic nucleon-nucleon interactions. A cutoff momentum Λ is introduced to specify a border between the low- and high-momentum spaces. By Faddeev-Yakubovsky calculations the low-momentum interactions are investigated with respect to the dependence of ground-state energies of ³H and ⁴He on the parameter Λ. It is found that we need the momentum cutoff parameter Λ50.3em0exfm^-1 in order to reproduce satisfactorily the exact values of the binding energies for ³H and ⁴He. The calculation with Λ=20.3em0exfm^-1 recommended by Bogner et al. leads to considerable overbinding at least for few-nucleon systems.