Resonating-group study of baryon-baryon interactions for the complete baryon octet:<i>NN</i>interaction

Abstract

The baryon-baryon interaction for the complete baryon octet is investigated in a unified framework of the resonating-group method which employs the spin-flavor ${\mathrm{SU}}_{6}$ wave functions with explicit color degrees of freedom. The interaction Hamiltonian is composed of the phenomenological confinement potential, the color Fermi-Breit interaction with explicit flavor symmetry breaking, and the effective meson-exchange potentials of scalar, pseudoscalar, and vector-meson types, acting between quarks. For the scalar- and vector-meson exchanges, the momentum-dependent higher-order terms are incorporated to reduce the attractive effect of the central interaction at higher energies. The single-particle potentials of the octet baryons, predicted by the G-matrix calculation, now have proper repulsive behavior in the momentum region ${q}_{1}=5--20 {\mathrm{fm}}^{\ensuremath{-}1}.$ A moderate contribution of the spin-orbit interaction from the scalar-meson exchange is also included. As to the vector mesons, a dominant contribution is the quadratic spin-orbit force generated from the $\ensuremath{\rho}$-meson exchange. This paper discusses the nucleon-nucleon interaction up to ${T}_{\mathrm{lab}}=800 \mathrm{MeV}.$ The nucleon-nucleon phase shifts at the nonrelativistic energies up to ${T}_{\mathrm{lab}}=350 \mathrm{MeV}$ are greatly improved, and now have attained the accuracy almost comparable to that of one-boson-exchange potentials. The deuteron properties and the low-energy observables of the nucleon-nucleon interaction are examined in the particle basis by incorporating the isospin symmetry breaking through the mass difference of the neutral and charged pions and the Coulomb effect as well. The nuclear saturation properties and the single-particle potential of the nucleon in symmetric nuclear matter are examined through the G-matrix calculation which uses the quark-exchange kernel directly.