  Using the path-integral formalism, we generalize the 't Hooft-Veltman method
of unitary regulators to put forward a framework for finite, alternative
quantum theories to a given quantum field theory. Feynman-like rules of such a
finite, alternative quantum theory lead to alternative, perturbative Green
functions. Which are acceptably regularized perturbative expansions of the
original Green functions, causal, and imply no unphysical free particles. To
demonstrate that the proposed framework is feasible, we take the quantum field
theory of a single, self-interacting real scalar field and show how we can
alter, covariantly and locally, its free-field Lagrangian to obtain finite,
alternative perturbative Green functions.
