  By a direct resummation of perturbation theory in the limit of very high
energy and small transferred momentum (the so-called ``eikonal'' limit), we
derive expressions for the truncated-connected quark, antiquark and gluon
propagators in an external gluon field, both for scalar and fermion gauge
theories. These are the basic ingredients to derive ``soft'' high-energy
parton-parton scattering amplitudes, using the LSZ reduction formulae and a
functional integral approach.
