Download Claudia Eberlein Mass, energy-level and magnetic

Claudia Eberlein Mass, energy‐level and magnetic‐moment shifts near surfaces The magnetic moment of an electron as predicted by the Dirac equation is well known to receive corrections from quantum electrodynamics, and the accurate prediction of g‐2 corrections is one of the big successes of QED. If the electromagnetic field is modified by the presence of a material boundary nearby, then this also affects the QED corrections to the magnetic moment. This effect had previously been investigated, but only for the spin close to a perfectly reflecting boundary, for which the magnitude of the correction is minute. We have now investigated the corrections to the spin magnetic moment due to the presence of imperfectly reflecting surfaces of various kinds: non‐dispersive dielectric as well as dispersive dielectric and metallic ones. We find that the magnetic moment shift is very different near different material boundaries, and that, while still very small, it can be several orders of magnitude bigger than previously predicted on the basis of perfect‐reflector models. The theory of the shift turns out to be markedly different from that of other cavity QED effects and results of different models cannot be recovered as limiting cases of each other. We have explored various methods of calculating the magnetic moment shift. The standard QED approach of working out the vertex correction is fraught with technical difficulties; perturbation theory in the Dirac equation is technically much easier.