LAUSR

The Alt–Grassberger–Sandhas equations for the five-body problem are solved for the case of the driving two-body potentials limited to s-waves. The separable pole expansion method is employed to convert the equations into the effective quasi-two-body form. Numerical results are presented for five identical bosons as well as for the system containing an $$\eta $$-meson and four nucleons. Accuracy of the separable expansion is investigated. It is shown that both in $$(1+4)$$ and $$(2+3)$$ fragmentation, the corresponding eigenvalues decrease rather rapidly, what, combined with the alternation of their signs, leads to rather good convergence of the results. For the $$\eta -4N$$ system the crucial influence of the subthreshold behavior of the $$\eta N$$ amplitude on the $$\eta $$-nuclear low-energy interaction is discussed.