Contribution of Three-Body Forces to the Binding of Hyperfragments

The potential energy of $\Lambda$ in the hypertriton due to two- and three-body pion-exchange forces is estimated. The contributions from the two types of forces are found to be of the same order of magnitude, thus indicating that the three-body force produces the binding of $\Lambda$ in the hypertriton. The role of the three-body force in the binding of other light hyperfragments is briefly discussed.