Soft-core nucleon-nucleon potential

The hard cores of the Hamada-Johnston1) (HJ) nucleon-nucleon potential are replaced by finite square wells of larger radius (0.7 fm), and it is demonstrated that the nucleon-nucleon scattering and deuteron data are very well fit by this specific static potential. Outside of the square-well radius the potential is the same as that of HJ except for a few small changes in some of their parameters. The pion masses differ from that of HJ in a charge-dependent way such that charge symmetry is retained. The radius of the square finite cores, which is about 0.7 fm, also has a small charge dependence such that charge symmetry is retained but charge dependence is violated. The strengths of the square cores for n-p and p-p scattering are determined by a computer search. The search routine utilizes a chi-squared test in which the scattering and deuteron data are fit directly. The current best fit obtained in the p-p case has a chi-squared value of about 2.0 per data point, which is smaller than that for any other potential tested against the p-p data set of Signell et al.2).