Four-body bound-state calculations in three-dimensional approach

The four-body bound state with two-body interactions is formulated in three-dimensional approach, a recently developed momentum-space representation which greatly simplifies the numerical calculations of few-body systems without performing the partial wave decomposition. The obtained three-dimensional Faddeev-Yakubovsky integral equations are solved with two-body spin-independent and spin-averaged potentials. This is the first step toward the calculations of the four-nucleon bound-state problem in three-dimensional approach. Results for four-body binding energies are in good agreement with achievements of the other methods.