We study effective models describing systems of quantum particles interacting with
quantized (electromagnetic) fields in the quasiclassical regime, i.e., when the field’s
state shows a large average number of excitations. Once the field’s degrees of
freedom are traced out on factorized states, the reduced dynamics of the
particles’ system is described by an effective Schrödinger operator keeping
track of the field’s state. We prove that, under suitable assumptions on the
latter, such effective models are well-posed even if the particles are point-like,
that is no ultraviolet cut-off is imposed on the interaction with quantum
fields.
Keywords
quasiclassical limits, nonrelativistic quantum
electrodynamics, point charge limit