Hypertriton: Λ⇆Σ conversion and tensor forces

The separable potential equations that describe the hypertriton when ΛN-ΣN coupling and noncentral NN and YN forces are included, are formulated. Numerical solution of the equations for various potential models shows that Λ-Σ conversion in the YN interaction plays a significant role, even in the lightly bound ${}_{\mathrm{\Lambda }}{}^3{}_{}{}^{}\mathrm{H}$. When the ΣN channel is formally eliminated, the dispersive energy dependence of the resulting ΛN effective interaction is repulsive, whereas the resulting ΛNN three-body force is attractive. The contribution of the ΛN tensor force is shown to depend upon the inclusion of the NN tensor force and the relative sign of the ${}_{}{}^3{}_{}{}^{}$ ${\mathit{S}}_1$ ${\mathrm{-}}^3$ ${\mathit{D}}_1$ NN and ΛN tensor coupling. Also, a model which supports a ΣN bound state in the continuum appears to severely overbind the ${}_{\mathrm{\Lambda }}{}^3{}_{}{}^{}\mathrm{H}$ system, indicating that such a phenomenon is not present in the ${\mathit{K}}^{\mathrm{-}}$d→ΛNπ reaction.