Motion of Spin-1/2 Particles in External Gravitational and Electromagnetic Fields

TL;DR

This paper investigates the semi-classical behavior of spin-1/2 particles in electromagnetic and gravitational plane wave backgrounds, linking quantum solutions to classical spinning particle dynamics.

Contribution

It provides exact solutions to the Dirac equation in external fields and explores their classical limits, proposing a connection between quantum spin and classical spin tensors.

Findings

Exact solutions align with classical spinning particle constraints

Wave-packet superpositions reveal particle motion in inhomogeneous fields

Ongoing work on classical spin tensor models

Abstract

(Talk presented at the 7th Marcel Grossmann Meeting on General Relativity, Stanford, CA, July 24-30, 1994) We study the semi-classical limit of the solution of the Dirac equation in a background electromagnetic/gravitational plane wave. We show that the exact solution corresponding to an asymptotically fixed incoming momentum satisfies constraints consistent with the classical notion of a spinning particle. In order to further analyze the motion of a spinning particle in this external inhomogeneous field one has to consider wave-packet superpositions of these exact solutions. We are currently investigating the existence of a classical theory of a phenomenological spin tensor which reproduces our quantum-mechanical results.