Multimomentum Hamiltonian Formalism in Quantum Field Theory
  The familiar generating functionals in quantum field theory fail to be true measures and, so they make the sense only in the framework of the perturbation theory. In our approach, generating functionals are defined strictly as the Fourier transforms of Gaussian measures in nuclear spaces of multimomentum canonical variables when field momenta correspond to derivatives of fields with respect to all world coordinates, not only to time. 
G.Sardanashvily (Department of Theoretical Physics, Moscow State   University, Moscow, Russia)