The three-baryon $\Lambda NN$ potential

Using a three-baryon $\Lambda NN$ potential having a spin-independent dispersive and a two-pion exchange components, realistic variational Monte Carlo calculations have been performed for the $\Lambda$-seperation energy for $^{5}_{\Lambda}$He. A relationship between strengths associated with both pieces of $\Lambda NN$ force giving exact experimental $\Lambda$-seperation energy has been obtained which then combined with our previous study on $^{17}_{\,\,\Lambda}$O hypernucleus determines a unique and acceptable set of strength parameters for $\Lambda NN$ potential. The $\Lambda NN$ force is found important for the core polarization.