2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/106034We establish the existence of Bogoliubov's local scattering operators for P(ϕ)_2 models of constructive quantum field theory in a nonperturbative way. To this end, we use the technique of evolution semigroups to prove a new result on wellposedness of the Cauchy problem for the time-dependent Schrödinger equation under very general assumptions.Ph.D. thesis, 121 pagesMathematical Physics35L90text