Boundary terms in quantum field theory and the spin structure of QCD
arXiv:1408.3233 · doi:10.1016/j.nuclphysb.2014.11.004
Abstract
Determining how boundary terms behave in a quantum field theory (QFT) is crucial for understanding the dynamics of the theory. Nevertheless, boundary terms are often neglected using classical-type arguments which are no longer justified in the full quantum theory. In this paper we address this problem by establishing a necessary and sufficient condition for arbitrary spatial boundary terms to vanish in a general QFT. As an application of this condition we examine the issue of whether the angular momentum operator in Quantum Chromodynamics (QCD) has a physically meaningful quark-gluon decomposition. Using this condition it appears as though this is not the case, and that it is in fact the non-perturbative QCD structure which prevents the possibility of such a decomposition.
arXiv comment14 pages; v2: references/discussion added and minor typos corrected, version published in Nucl.Phys.B
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- A still unsettled issue in the nucleon spin decomposition problem : On the role of surface terms and gluon topology
- Proton spin: a topological invariant
- Gauge Invariant Noether's Theorem and The Proton Spin Crisis