Particle Mixing and Charge Asymmetric Λ N Forces

We calculate the contributions of a particular set of charge asymmetric $\Lambda N$ interactions to the difference of the separation energies of $^4_{\Lambda}$He and $^4_{\Lambda}$H. We use perturbation theory with four-body variational Monte Carlo wave functions calculated from a Hamiltonian with two- and three-hadron forces. We compare with the data and with an earlier calculation made by one of us which employed a two-body wave function of the $\Lambda$-nucleus type.