“…We should point out that despite the approximations concerning the spatial dimensions, the fermions' spin directions, and non-vanishing mass of the model photons, due to its fundamental character this Hamiltonian (and its reduced versions) has been studied in a wide variety of contexts. For example, to name a few, this includes the examination of the origin of attractive and repulsive interfermionic forces due to the exchange of intermediating photons [23], the evolution of bare electrons into physical electrons under photon emission [24,25], a space-time resolved Compton scattering [26], the formation of fermion bound states in the perturbative and also Borel summable non-perturbative regimes [22,27,28].…”