Noetherian Conservation Laws for Photons
Michael K. -H. Kiessling, A. Shadi Tahvildar-Zadeh
TL;DR
This work develops Noetherian, gauge-invariant conservation laws for a Lorentz-covariant photon wave equation expressed as a rank-two bispinor on Minkowski space, embedding the theory in a Clifford-algebra framework. It establishes a 10-dimensional family of conserved currents, of which eight yield global, ADM-like charges that converge to gauge-invariant, asymptotic quantities defining a covariantly constant self-dual bispinor. The analysis extends to curved spacetimes, where boundary currents are constructed to obtain ADM-like invariants at infinity, and an explicit Minkowski-space example demonstrates the existence of a nontrivial bispinor at infinity while preserving gauge invariance. The results illuminate how Noether's theorems continue to yield physically meaningful, global conserved quantities for gauge theories of massless spin-one particles, even in settings with limited spacetime symmetries, and suggest a robust link between asymptotic charges and self-duality in the photon sector.$
Abstract
We review the formulation of a Lorentz-covariant bispinorial wave function and wave equation for a single photon on a flat background. We show the existence of a 10-dimensional set of conservation laws for this equation, and prove that 8 of these can be used to obtain global, gauge-invariant, ADM-like quantities that together define a covariantly constant self-dual bispinor.
