Scattering theories in models of quantum electrodynamics

This thesis is devoted to the analysis of solvable hamiltonian models, with the purpose of understanding and possibly filling the gap that still separates the standard methods, used to circumvent the infrared divergences occurring in the local and covariant Feynman-Dyson expansion of Quantum Electrodynamics, from a formulation of scattering in which the non-perturbative features of the infrared problem are taken into account