General Electromagnetic Nonminimal Couplings in the Dirac Equation

TL;DR

This paper introduces a new class of Lorentz-violating, CPT-even nonminimal couplings in the Dirac equation that generate electric and magnetic dipole moments, constrained by precise electron measurements.

Contribution

It proposes a novel dimension-five, nonminimal fermion-photon interaction framework without higher derivatives, expanding the understanding of Lorentz violation in quantum field theory.

Findings

Upper bounds of $1$ part in $10^{11}$ GeV$^{-1}$ from magnetic dipole moment measurements.

Upper bounds of $10^{16}$ GeV$^{-1}$ from electric dipole moment measurements.

The couplings are constructed from a rank-2 tensor, electromagnetic tensor, and gamma matrices.

Abstract

We examine a new class of CPT-even and dimension-five nonminimal interactions between fermions and photons, deprived of higher-order derivatives, yielding electric dipole moment and magnetic dipole moment in the context of the Dirac equation. These couplings are Lorentz-violating nonminimal structures, composed of a rank-2 tensor, the electromagnetic tensor, and gamma matrices, being addressed in its axial and non-axial hermitian versions. We use the electron's anomalous magnetic and electric dipole moment measurements to reach upper bounds of $1$ part in $10^{11}$ and $10^{16}$ GeV$^{-1}$.