S-matrix calculus using effective particles in the Fock space

This article describes a method for calculating S-matrix elements using Hamiltonians obtained in the renormalization group procedure for effective particles. It is shown that the scattering amplitudes obtained using a canonical Hamiltonian $H^\Delta$ with counterterms are the same as those obtained using a renormalized Hamiltonian for effective particles, $H_\lambda$. The result is independent of the ultraviolet cutoff $\Delta$ and the renormalization-group parameter $\lambda$.