  We consider the ground state in a model with scalar nucleons and a meson
using the formalism of light-front dynamics. Light-front potentials for
two-nucleon bound states are calculated using two approaches. First,
light-front time-ordered perturbation theory is used to calculate one- and
two-meson-exchange potentials. These potentials give results that agree well
with the ladder and ladder plus crossed box Bethe-Salpeter spectra. Secondly,
approximations that incorporate non-perturbative physics are used to calculate
alternative one-meson-exchange potentials. These non-perturbative potentials
give better agreement with the spectra of the full non-perturbative
ground-state calculation than the perturbative potentials. For lightly-bound
states, all of the approaches appear to agree with each other.
