Variational approach to the bound-state Faddeev equations

A variational principle for the bound-state Faddeev equations is given. This principle takes the form of a variational expression for the linear eigenvalues of the Faddeev kernel. The variational expression is investigated for the case in which the wave function is expanded in terms of known functions. In this case it can be reduced to the variational method of Rosenberg, and hence the energies obtained are variational upper bounds for the bound-state energy. The variational expression is also used to generate a new set of one-dimensional integral equations for the bound-state problem.