Status of understanding the YN/YY-interactions Meson-exchange viewpoint

Abstract

We analyze and discuss the extended-soft-core models ESC04 and ESC08, which at present are 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) S U F ( 3 ) -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, and (v) quark-core effects. In the OBE-sector, special features are the importance of the axial-vector meson potentials, and the inclusion of a zero in the scalar- and axial-meson form-factors. Novel for the ESC08-versions is the inclusion of (a) odderon-exchange, and (b) 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 P 0 3 quark-pair-creation model (QPC), although in ESC08a,b a certain admixture of S 1 3 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 χ p . d . p . 2 = 1.180 and 1.135 for respectively ESC08a and ESC08b. Also, we improved the Λ N 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 ample repulsion in the Σ + p ( S 1 3 , T = 3 / 2 ) - and Σ N ( S 0 1 , T = 1 / 2 ) -channels.