Mass and Magnetic Moment of the Electron and the Stability of QED—A Critical Review

The anomalous magnetic moment of the electron, first calculated by Schwinger, lowers the ground state energy of the electron in a weak magnetic field. It is a function of the field and changes signs for large fields, ensuring the stability of the ground state. This has been shown in the past 50 years in numerous papers. The corresponding corrections to the mass of the electron have also been investigated in strong fields using semiclassical methods. We critically review these developments and point out that the calculation for low-lying excited states raises questions. Also, we calculate the contribution from the tadpole diagram, the relevance of which was observed only quite recently.