Three-body structure of the $nn\mathrm{\Lambda }$ system with $\mathrm{\Lambda }N-\mathrm{\Sigma }N$ coupling

The structure of the three-body $nn\mathrm{\Lambda }$ system, which has been observed recently by the HypHI collaboration, is investigated taking $\Lambda N-\Sigma N$couplingexplicitlyintoaccount\mathrm{.}The$YN$and$NN$ interactions employed in this work reproduce the binding energies of ${}_{\mathrm{\Lambda }}^3$H, ${}_{\mathrm{\Lambda }}^4$H and ${}_{\mathrm{\Lambda }}^4$He. We do not find any ${}_{\mathrm{\Lambda }}^{3}n$ bound state, which contradicts the interpretation of the data reported by the HypHI collaboration.