Quark angular momentum in a spectator model

Abstract

We investigate the quark angular momentum in a model with the nucleon being a quark and a spectator. Both scalar and axial-vector spectators are included. We perform the calculations in the light-cone formalism where the parton concept is well defined. We calculate the quark helicity and canonical orbital angular momentum. Then we calculate the gravitational form factors which are often related to the kinetic angular momentums, and find that even in a no gauge field model we cannot identify the canonical angular momentums with half the sum of gravitational form factors. In addition, we examine the model relation between the orbital angular momentum and pretzelosity, and find it is violated in the axial-vector case.

6 pages, final version to appear in PLB

References in corpus (14)

• Evidence for polarization of gluons in the proton
• The Deuteron Spin-dependent Structure Function g1d and its First Moment
• Transverse-momentum distributions in a diquark spectator model
• Quark Wigner Distributions and Orbital Angular Momentum
• Reply to the Comment on "Spin and orbital angular momentum in gauge theories: Nucleon spin structure and multipole radiation revisited" [PRL 100:232002 (2008)]
• Spin and orbital angular momentum in gauge theories: Nucleon spin structure and multipole radiation revisited
• Do gluons carry half of the nucleon momentum?
• Pretzelosity $h_{1T}^{\perp }$ and quark orbital angular momentum
• Gauge- and frame-independent decomposition of nucleon spin
• Implication of the overlap representation for modelling generalized parton distributions
• On the controversy concerning the definition of quark and gluon angular momentum
• Angular momentum decomposition from a QED example
• Generalized form factors of the nucleon in a light-cone spectator-diquark model
• Quark orbital motions from Wigner distributions