Single-particle spin-orbit strengths of the nucleon and hyperons by SU6 quark-model

摘要

The quark-model hyperon-nucleon interaction suggests an important antisymmetric spin-orbit component. It is generated from a color analogue of the Fermi-Breit interaction dominating in the one-gluon exchange process between quarks. We discuss the strength S-B of the single-particle spinorbit potential, following the Scheerbaum's prescription. Using the SU6 quark-model baryon-baryon interaction which was recently developed by the Kyoto-Niigata group, we calculate NN, Lambda N and Sigma N G-matrices in symmetric nuclear matter and apply them to estimate the strength S-B. The ratio of S-B to the nucleon strength S-N similar to -40 MeVfm(5) is S-Lambda/S-N similar to 1/5 and S-Sigma/S-N similar to 1/2 in the Born approximation. The G-matrix calculation of the model FSS modifies S-Lambda to S-Lambda/S-N similar to 1/12. For S-N and S-Sigma, the effect of the short-range correlation is comparatively weak against meson-exchange potentials with a short-range repulsive core. The significant reduction of the Lambda single-particle potential arises from the combined effect of the antisymmetric LS force, the flavor-symmetry breaking originating from the strange to up-down quark-mass difference, as well as the effect of the short-range correlation. The density dependence of S-B is also examined. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 29]