  Gauge fields in the light front are traditionally addressed via the
employment of an algebraic condition $n\cdot A=0$ in the Lagrangian density,
where $A_{\mu}$ is the gauge field (Abelian or non-Abelian) and $n^\mu$ is the
external, light-like, constant vector which defines the gauge proper. However,
this condition though necessary is not sufficient to fix the gauge completely;
there still remains a residual gauge freedom that must be addressed
appropriately. To do this, we need to define the condition $(n\cdot A)(\partial
\cdot A)=0$ with $n\cdot A=0=\partial \cdot A$. The implementation of this
condition in the theory gives rise to a gauge boson propagator (in momentum
space) leading to conspicuous non-local singularities of the type $(k\cdot
n)^{-\alpha}$ where $\alpha=1,2$. These singularities must be conveniently
treated, and by convenient we mean not only matemathically well-defined but
physically sound and meaningfull as well. In calculating such a propagator for
one and two noncovariant gauge bosons those singularities demand from the
outset the use of a prescription such as the Mandelstam-Leibbrandt (ML) one. We
show that the implementation of the ML prescription does not remove certain
pathologies associated with zero modes. However we present a causal,
singularity-softening prescription and show how to keep causality from being
broken without the zero mode nuisance and letting only the propagation of
physical degrees of freedom.
