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.

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

References in corpus (9)

• The Deuteron Spin-dependent Structure Function g1d and its First Moment
• Nucleon form-factors of the energy momentum tensor in the chiral quark-soliton model
• MRST partons generated in a fixed-flavour scheme
• The pion mass dependence of the nucleon form-factors of the energy momentum tensor in the chiral quark-soliton model
• Evidence for the Absence of Gluon Orbital Angular Momentum in the Nucleon
• Generalized form factors, generalized parton distributions and the spin contents of the nucleon
• Pion mass dependence of the nucleon mass in the chiral quark soliton model
• Equivalence Principle and Partition of Angular Momenta in the Nucleon
• Polarized Gluon Distribution Delta g(x) in the Proton

Cited by in corpus (6)

• The transverse momentum dependent distribution functions in the bag model
• Interplay of Spin and Orbital Angular Momentum in the Proton
• Gauge- and frame-independent decomposition of nucleon spin
• Transverse momentum distributions of quarks in the nucleon from the Chiral Quark Soliton Model
• Chiral-odd generalized parton distributions, transversity decomposition of angular momentum, and tensor charges of the nucleon
• On the physics behind the form factor ratio ${\mu }_p{G}_E^p(Q^2)/G_M^p(Q^2)$