  Canonically, the quantum electrodynamic radiative corrections in bound
systems have been evaluated in photon energy regularization, i. e. using a
noncovariant overlapping parameter that separates the high-energy relativistic
scales of the virtual quanta from the nonrelativistic domain. Here, we
calculate the higher-order corrections to the one-photon self-energy
calculation with three different overlapping parameters (photon energy, photon
mass and dimensional regularization) and demonstrate the reparameterization
invariance of nonrelativistic quantum electrodynamics (NRQED) using this
particular example. We also present new techniques for the calculation of the
low-energy part of this correction, which lead to results for the Lamb shift of
highly excited states that are important for high-precision spectroscopy.
