  The four-body Yakubovsky equations in a Three-Dimensional approach with the
inclusion of the three-body forces is proposed. The four-body bound state with
two- and three-body interactions is formulated in Three-Dimensional approach
for identical particles as function of vector Jacobi momenta, specifically the
magnitudes of the momenta and the angles between them. The modified three
dimensional Yakubovsky integral equations is successfully solved with the
scalar two-meson exchange three-body force where the Malfliet-Tjon-type
two-body force is implemented. The three-body force effects on the energy
eigenvalue and the four-body wave function, as well as accuracy of our
numerical calculations are presented.The four-body Yakubovsky equations in a
Three-Dimensional approach with the inclusion of the three-body forces is
proposed. The four-body bound state with two- and three-body interactions is
formulated in Three-Dimensional approach for identical particles as function of
vector Jacobi momenta, specifically the magnitudes of the momenta and the
angles between them. The modified three dimensional Yakubovsky integral
equations is successfully solved with the scalar two-meson exchange three-body
force where the Malfliet-Tjon-type two-body force is implemented. The
three-body force effects on the energy eigenvalue and the four-body wave
function, as well as accuracy of our numerical calculations are presented.
