Exact Results in Quantum Theory & Gravity

I will start the talk with a brief discussion of not-so-intuitive expressions for angular momentum operators of the covariantly quantized electromagnetic field. I will then discuss radiative corrections to various components of angular momentum of the electron (e.g. spin and orbital components associated with fermionic and electromagnetic degrees of freedom). The reported results come from one-loop calculations performed in the general covariant gauge. Technical aspects of these studies, such as a not-so-obvious Pauli-Villars-like regularization of the calculations, will be commented upon.