  We lay out the basis of factorization at the amplitude level for processes
involving the entire Standard Model. The factorization appears in a generalized
eikonal approximation in which we expand around a quasi-soft limit for massive
gauge bosons, fermions, and scalars. We use the chirality-flow formalism to
express loop exchanges or emissions as operators on chiral structures. This
forms the basis for amplitude evolution with parton exchange and branching in
the full Standard Model, including the electroweak sector.
