Physical consequences of the QED theta angle

TL;DR

This paper explores the physical effects of the QED theta angle through a thought experiment, revealing quantum phases similar to the Aharonov-Bohm effect and extending the analysis to non-Abelian gauge theories.

Contribution

It introduces a simple gedanken experiment to illustrate the physical consequences of the QED theta angle and generalizes the quantum phase analysis to non-Abelian gauge theories.

Findings

QED theta angle induces measurable quantum phases

Quantum phases are analogous to Aharonov-Bohm effect

Results extend to non-Abelian gauge theories

Abstract

We describe a simple gedanken experiment which illustrates the physical effects of the QED theta angle, a fundamental parameter of Nature that has yet to be measured. The effects are manifest in quantum phases analogous to those in the Aharonov-Bohm effect, although they are not intrinsically topological. We also derive the quantum phases using a functional Schrodinger approach, and generalize the results to non-Abelian gauge theories.