Electron interaction with the angular momentum of the electromagnetic field

TL;DR

This paper presents a simple derivation of a new relativistic interaction between electrons and the angular momentum of electromagnetic fields in quantum electrodynamics, extending Mollers classical results to the quantum regime.

Contribution

It introduces a novel relativistic interaction term in QED and generalizes Mollers classical findings to quantum theory, linking spin and electromagnetic angular momentum.

Findings

Derivation of a new energy contribution in QED due to electron-field interaction.

Extension of Mollers classical results to quantum regime.

All spin terms from the Dirac equation can be derived using this method.

Abstract

We give a simple derivation and explanation of a recently proposed new relativistic interaction between the electron and the angular momentum of the electromagnetic field in quantum electrodynamics (QED). Our derivation is based on the work of Moller, who pointed out that, in special relativity, a particle with spin must always have a finite extension. We generalize Mollers classical result to the quantum regime and show that it leads to a new contribution to the energy, which is the special relativistic interaction term. In addition, we show that all spin terms arising from the Dirac equation may be obtained by this method.