Baryon–Baryon {8}\( \otimes \){8}-Channels Interactions

Abstract

The extended-soft-core model ESC08 is presented. The ESC-models are at present the most complete meson-exchange models for the baryon–baryon interactions. The ESC-model describes the nucleon–nucleon (NN), hyperon–nucleon (YN), and hyperon–hyperon (YY), in terms of meson-exchanges using (broken) SU(3)f-symmetry. In this approach to baryon-baryon (BB) the dynamics is derived from (i) one-boson-exchanges (OBE), (ii) two-meson-exchanges (TME), and (iii) meson-pair-exchanges (MPE), (iv) gluon-exchanges in the form of the pomeron and odderon potentials, and (v) quark-core effects. In the OBE-sector, special features are: (a) the inclusion of a zero in the scalar- and axial- meson form-factors, (b) the odderon-exchage representing the exchange of the odd-number gluons-exchange, whereas the pomeron represents the even-number gluon-exchange, and (c) special pronounced effects of the appearance of forbidden six-quark configurations. With these ingredients a rather flexible dynamical framework is constructed. Namely, it appeared feasible to keep the parameters of the model in reasonable accordance with the predictions of the ^3P_0 quark-pair-creation model (QPC), although in ESC08a,b,c an admixture of ^3S_1 quark-pair creation is present. This is the case for the meson- and meson-pair-baryon coupling constants and the F/(F+D)-ratio’s as well. The NN, YN, and YY results for this model are excellent. This is marked in particularly by the NN-results, namely \(\chi _{p.d.p.}^{2} = 1.08\) for ESC08a,b,c. Also, we improved the ΛN spin–orbit interaction greatly by the inclusion of (a) the Brown, Downs, and Iddings anti-symmetric spin–orbit potentials, and (b) new corrections to the MPE-potentials. Also, the special quark-core effects provide extra repulsion in the Σ^+p(^3S_1, T = 3/2)- and ΣN(^1S_0, T = 1/2)-channels, although the strength is constrained by SU(3) symmetry and the Σ^+p experimental X-sections. In the S = −2 sector the ΛΛ-interaction is weak, which is in accordance with the NAGARA-event. Furthermore, in the ΞN(^3S_1, I = 1) there occurs a “strange-deuteron” D^* with binding-energy \(E_{B}^{*} \approx 2.0 - 1.5\) MeV. A very notable consequence of the MPE-vertices are the related three-body forces (TBF). In this conference we report on the predictions of these TBF’s for (i) the triton binding energy, and (ii) the charge-symmetry-breaking (CSB) effects. The first results are encouraging.