  We show that, in the light-cone gauge, it is possible to derive in a very
simple way the solution of the classical Yang-Mills equations for the collision
between a nucleus and a proton. One important step of the calculation is the
derivation of a formula that describes the propagation of a gluon in the
background color field of the nucleus. This allows us to calculate observables
in pA collisions in a more straightforward fashion than already proposed. We
discuss also the comparison between light-cone gauge and covariant gauge in
view of further investigations involving higher order corrections.
