Effective Angular Momentum Operators in NRQED and Matching at One-Loop Order

TL;DR

This paper derives the effective angular momentum operators in NRQED up to order 1/m^2 and one-loop, providing essential tools for precision calculations of angular momentum in non-relativistic atomic systems.

Contribution

It presents the derivation of the angular momentum operators in NRQED at one-loop and 1/m^2 order, including regularization scheme comparisons.

Findings

Derived non-relativistic expansion for electron and photon angular momentum operators.

Provided results in both dimensional and cutoff regularization schemes.

Facilitated more accurate angular momentum calculations in atomic physics.

Abstract

We derive the effective angular momentum operator to $1/m^2$ and one-loop order in non-relativistic quantum electrodynamics (NRQED). In both dimensional and three-momentum-cutoff regularization schemes, we obtain the non-relativistic expansion for the spin and orbital angular momentum operators of the electron and photon, respectively. Our result is useful in precision calculations of the angular momentum properties for non-relativistic QED bound states, such as atom systems.