Art of spin decomposition
Abstract
We analyze the problem of spin decomposition for an interacting system from a natural perspective of constructing angular momentum eigenstates. We split, from the total angular momentum operator, a proper part which can be separately conserved for a stationary state. This part commutes with the total Hamiltonian and thus specifies the quantum angular momentum. We first show how this can be done in a gauge-dependent way, by seeking a specific gauge in which part of the total angular momentum operator vanishes identically. We then construct a gauge-invariant operator with the desired property. Our analysis clarifies what is the most pertinent choice among the various proposals for decomposing the nucleon spin. A similar analysis is performed for extracting a proper part from the total Hamiltonian to construct energy eigenstates.
Keywords
Cite
@article{arxiv.1105.6304,
title = {Art of spin decomposition},
author = {Xiang-Song Chen and Wei-Min Sun and Fan Wang and T. Goldman},
journal= {arXiv preprint arXiv:1105.6304},
year = {2011}
}
Comments
5 pages, no figure; published in Phys.Rev.D (Rapid Communications)