Possibility of generating a 4-neutron resonance with a\(T=3/2\)isospin 3-neutron force

We present an updated version (Nijm93) of the Nijmegen soft-core potential, which gives a much better description of the np data than the older version (Nijm78). The chi^2 per datum is 1.87. The configuration-space and momentum-space versions of this potential are exactly equivalent; a unique feature among meson-theoretical potentials. We also present three new NN potential models: a non-local Reid-like Nijmegen potential (NijmI), a local version (NijmII), and an updated regularized version (Reid93) of the Reid soft-core potential. These three potentials all have a nearly optimal chi^2 per datum and can therefore be considered as alternative partial-wave analyses. All potentials contain the proper charge-dependent one-pion-exchange tail. Fortran code for the potentials can be obtained via anonymous ftp from thef-nym.sci.kun.nl

We present a new high-quality nucleon-nucleon potential with explicit charge dependence and charge asymmetry, which we designate Argonne \(v_{18}\). The model has a charge-independent part with fourteen operator components that is an updated version of the Argonne \(v_{14}\) potential. Three additional charge-dependent and one charge-asymmetric operators are added, along with a complete electromagnetic interaction. The potential has been fit directly to the Nijmegen \(pp\) and \(np\) scattering data base, low-energy \(nn\) scattering parameters, and deuteron binding energy. With 40 adjustable parameters it gives a \(\chi^{2}\) per datum of 1.09 for 4301 \(pp\) and \(np\) data in the range 0--350 MeV.