  It is often said that soliton contributions to perturbative processes in QFT
are exponentially suppressed by a form factor. We provide a new derivation of
this form factor for a class of scalar theories with generic soliton moduli.
The derivation treats the soliton momenta relativistically and is valid at
leading order in momentum transfer. The computation reduces to a matrix element
in the quantum mechanics on the soliton moduli space. We investigate the
conditions under which the latter leads to suppression. Extending this
framework to instanton-solitons in five-dimensional Yang-Mills theory leaves
open the possibility that such contributions will not be suppressed.
