Phenomenological analysis of the nucleon spin contents and their scale dependence

Abstract

In the past few years, a lot of evidences have been accumulated, which indicate that the gluon polarization inside the nucleon is likely to be small at least at the low renormalization scales. On the other hand, the recent lattice QCD analyses suggest that the net orbital angular momentum carried by the quarks is nearly zero. There is also some indication noticed by Brodsky and Gardner based on the COMPASS observation of small single-spin asymmetry on the isoscalar deuteron target, that the gluon orbital angular momentum inside the nucleon is likely to be small. Naively combining all these observations, we are led to a rather embarrassing conclusion that the nucleon constituents altogether do not carry enough amount of angular momentum saturating the total nucleon spin. We show that this somewhat confused state of affairs can be cleared up only by paying careful attention to the scale dependencies of the nucleon spin decomposition.

arXiv comment35 pages, 8 figures, 2 tables, title has been changed, version to appear in Phys. Rev. D

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Cited by in corpus (19)

• Nucleon structure from mixed action calculations using 2+1 flavors of asqtad sea and domain wall valence fermions
• The transverse momentum dependent distribution functions in the bag model
• The Spin Structure of the Nucleon
• Interplay of Spin and Orbital Angular Momentum in the Proton
• On Gauge-Invariant Decomposition of Nucleon Spin
• Constraining quark angular momentum through semi-inclusive measurements
• Is gauge-invariant complete decomposition of the nucleon spin possible ?
• Gauge- and frame-independent decomposition of nucleon spin
• Nucleon spin structure and pQCD frontier on the move
• Transverse momentum distributions of quarks in the nucleon from the Chiral Quark Soliton Model
• The role of orbital angular momentum in the proton spin
• More on the relation between the two physically inequivalent decompositions of the nucleon spin and momentum
• Chiral-odd generalized parton distributions, transversity decomposition of angular momentum, and tensor charges of the nucleon
• Spin of ground state baryons
• Are there infinitely many decompositions of the nucleon spin ?
• Spin structure of the nucleon: QCD evolution, lattice results and models
• Contribution of Orbital Angular Momentum to the Nucleon Spin
• Gauge-invariant decomposition of nucleon spin
• On the physics behind the form factor ratio ${\mu }_p{G}_E^p(Q^2)/G_M^p(Q^2)$