Solution of the renormalization problem in nonrelativistic quantum electrodynamics

The renormalization problem is solved without using the mass renormalization concept, by introducing a new physical interaction picture in which the unobservable interaction of the free electron with the vacuum radiation field is eliminated. This is achieved by applying a self-consistent projection-operator method developed by the author. A finite expression for the nonrelativistic Lamb shift, whose explicit evaluation shows a fairly good agreement with the experiment, is derived.