Extended-soft-core Baryon-Baryon Model ESC08 I. Nucleon-Nucleon Scattering

Abstract

The Nijmegen extended-sft-core ESC08c model for the baryon-baryon (BB) interactions of the SU(3) flavor-octet of baryons ($N, \Lambda, \Sigma$, and $\Xi$) is presented. In this first of a series of papers, the NN results are reported in detail. In the spirit of the Yukawa-approach to the nuclear force problem, the interactions are studied from the meson-exchange picture viewpoint, using generalized soft-core Yukawa-functions. These interactions are supplemented with (i) multiple-gluon-exchange, and (ii) structural effects due to the quark-core of the baryons. The extended-soft-core (ESC) meson-exchange interactions consist of local- and non-local-potentials due to ((i) One-boson-exchanges (OBE, which are the members of nonets of pseudoscalar , vector, scalar, and axial-vector mesons, (ii) diffractive (i.e. multiple-gluon) exchanges, (iii) two pseudoscalar exchange (PS-PS), and (iv) meson-pair-exchange (MPE). The OBE- and MPE-vertices are regulated by gaussian form factors producing potentials with a soft behavior near the origin. The assignment of the cut-off masses for the BBM-vertices is dependent on the SU(3)-classification of the exchanged mesons for OBE, and a similar scheme for MPE. The simultaneous fit of the ESC-models to the NN- and YN-scattering data achieved excellent results for the NN, YN, and favorable properties for the $\Lambda\Lambda$ and $\Xi N$ systems. In the case of ESC08c, the version of this paper, the results are: (i) For the selected 4313 pp and np scattering data ($ 0 \leq T_{lab} \leq 350$ MeV), the model achieved $\chi^2/N_{data} = 1.08$. (ii) The deuteron binding energy and all NN low energy parameters are fitted very nicely. (iii) The YN-data are described also very well with $\chi^/N_{data} = 1.09$. (iv) The model predicts a bound $\Xi N(^3S_1,I=1)$ states with binding energy 1.56 MeV.