  In the paper we consider non-relativistic analog of the Nambu-Jona-Lasinio
model and demonstrate, by this most simplified example, the method of dynamical
mappings of Heisenberg fields on "physical" fields. We obtain the expressions
for one particle eigen-excitation spectrum of full Hamiltonian (spectrum of
"clad" fermions), wave function of two excitations' bound state and its mass,
and compute the Bethe-Solpither amplitude. We derive as well the relation for
the density of vacuum energy as a function of mapping parameters. The
minimization of energy leads us to the fixation of these parameters. The method
admits the generalization on the relativistic case.
