Unified Description ofNNandYNInteractions in a Quark Model with Effective Meson-Exchange Potentials

A simultaneous description of the NN and YN interactions is attempted in the resonating-group formulation of the spin-flavor S${\mathrm{U}}_6$ quark model, in which the full Fermi-Breit interaction with explicit quark-mass dependence acts between quarks, and all the mesons of scalar and pseudoscalar nonets couple directly to quarks. An overall agreement with the existing data is obtained with few adjustable parameters. In the $\Lambda p$ elastic total cross sections, the cusp structure at the $\Sigma N$ threshold is strongly enhanced by the antisymmetric ${\mathrm{LS}}^{\left(-\right)}$ force generated from the Fermi-Breit interaction.