  Within the covariant formulation of light-front dynamics, we calculate the
state vector of a physical fermion in the Yukawa model. The state vector is
decomposed in Fock sectors and we consider the first three ones: the single
constituent fermion, the constituent fermion coupled to one scalar boson, and
the constituent fermion coupled to two scalar bosons. This last three-body
sector generates nontrivial and nonperturbative contributions to the state
vector, which are calculated numerically. Field-theoretical divergences are
regularized using Pauli-Villars fermion and boson fields. Physical observables
can be unambiguously deduced using a systematic renormalization scheme we have
developed previously. As a first application, we consider the anomalous
magnetic moment of the physical fermion.
