About spin precession in electromagnetic wave

TL;DR

This paper demonstrates that two different theoretical approaches to describing spin precession in a circularly polarized electromagnetic wave yield consistent results up to second order in the wave's field, regardless of wavelength.

Contribution

It shows the equivalence of the Bargmann-Michel-Telegdi and Dirac with Pauli term approaches for spin precession in electromagnetic waves.

Findings

Both methods agree in second order calculations.

Results are valid for arbitrary wave length.

The approaches are theoretically consistent.

Abstract

It is shown that two ways of the description of the 1/2-spin precession in a circularly polarized electromagnetic wave: on the basis of the Bargmann-Michel-Telegdi equation and on the basis of the Dirac equation with Pauli term give the same result in the second order on the wave's field for arbitrary wave length.