Phenomenological Lambda-Nuclear Interactions
Variational Monte Carlo calculations for ${_Λ^4}H$ (ground and excited states) and ${_Λ^5}He$ are performed to decipher information on $Λ$-nuclear interactions. Appropriate operatorial nuclear and $Λ$-nuclear correlations have been incorporated to minimize the expectation values of the energies. We use the Argonne $\upsilon_{18}$ two-body NN along with the Urbana IX three-body NNN interactions. The study demonstrates that a large part of the splitting energy in ${_Λ^4}H$ ($0^+-1^+$) is due to the three-body $Λ$ NN forces. $_Λ^{17}O$ hypernucleus is analyzed using the {\it s}-shell results. $Λ$ binding to nuclear matter is calculated within the variational framework using the Fermi-Hypernetted-Chain technique. There is a need to correctly incorporate the three-body $Λ$ NN correlations for $Λ$ binding to nuclear matter.