Spin and orbital angular momentum in gauge theories: Nucleon spin structure and multipole radiation revisited

Jun, 2008
4 pages
Published in:
  • Phys.Rev.Lett. 100 (2008) 232002
e-Print:

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Abstract: (arXiv)
We address and solve the long-standing gauge-invariance problem of the nucleon spin structure. Explicitly gauge-invariant spin and orbital angular momentum operators of quarks and gluons are obtained. This was previously thought to be an impossible task, and opens a more promising avenue towards the understanding of the nucleon spin. Our research also justifies the traditional use of the canonical, gauge-dependent angular momentum operators of photons and electrons in the multipole-radiation analysis and labeling of atomic states/ and sheds much light on the related energy-momentum problem in gauge theories, especially in connection with the nucleon momentum.
  • 11.15.-q
  • 12.38.-t
  • 14.20.Dh
  • quantum electrodynamics
  • quantum chromodynamics
  • nucleon: spin
  • invariance: gauge
  • quark: spin
  • quark: angular momentum
  • radiation: multipole