Quantum Electrodynamics. III. The Electromagnetic Properties of the Electron—Radiative Corrections to Scattering

作者：Julian Schwinger · 发表于：Physical Review · 年份：1949 · DOI：10.1103/physrev.76.790 · 被引用次数：544 · 研究领域：Quantum and Classical Electrodynamics、Quantum Electrodynamics and Casimir Effect、Quantum Mechanics and Applications

The discussion of vacuum polarization in the previous paper of this series was confined to that produced by the field of a prescribed current distribution. We now consider the induction of current in the vacuum by an electron, which is a dynamical system and an entity indistinguishable from the particles associated with vacuum fluctuations. The additional current thus attributed to an electron implies an alteration in its electromagnetic properties which will be revealed by scattering in a Coulomb field and by energy level displacements. This paper is concerned with the computation of the second-order corrections to the current operator and the application to electron scattering. Radiative corrections to energy levels will be treated in the next paper of the series. Following a canonical transformation which effectively renormalizes the electron mass, the correction to the current operator produced by the coupling with the electromagnetic field is developed in a power series, of which first- and second-order terms are retained. One thus obtains second-order modifications in the current operator which are of the same general nature as the previously treated vacuum polarization current, save for a contribution that has the form of a dipole current. The latter implies a fractional increase of $\frac{\ensuremath{\alpha}}{2\ensuremath{\pi}}$ in the spin magnetic moment of the electron. The only flaw in the second-order current correction is a logarithmic divergence attributable to...