Effects of Instantons on the YN Interaction

Abstract

We investigate the symmetric and anti-symmetric spin-orbit forces (SLS and ALS) of the effective $Λ$N interaction derived from a quark cluster model with the instanton-induced interaction (\III), which can reproduce the observed YN cross sections as well as the observed NN scattering data. It is found that coupling to the $Σ$N channel enhances $Λ$N ALS, and therefore that the cancellation between SLS and ALS in the $Λ$N channel becomes more complete. This may be one of the major reasons why the single-particle spin-orbit force of $Λ$ in nuclei is weak.