Proton spin in leading order of the covariant approach

Abstract

We study the covariant version of the quark-parton model, in which the general rules of the angular momentum composition are accurately taken into account. We demonstrate how these rules affect the relativistic interplay between the quark spins and orbital angular momenta, which collectively contribute to the proton spin. The spin structure functions $g_1$ and $g_2$ corresponding to the many-quark state $J=1/2$ are studied and it is shown they satisfy constraints and relations well compatible with the available experimental data including proton spin content $\Delta \Sigma \lesssim 1/3$. The suggested Lorentz invariant 3D approach for calculation of the structure functions is compared with the approach based on the conventional collinear parton model.

19 pages, 1 figure, 3 tables

References in corpus (8)

• The Spin Structure of the Nucleon
• The Deuteron Spin-dependent Structure Function g1d and its First Moment
• Transverse-Spin and Transverse-Momentum Effects in High-Energy Processes
• Spin Structure of the Nucleon - Status and Recent Results
• Transverse momentum dependent distribution functions in a covariant parton model approach with quark orbital motion
• The relation between TMDs and PDFs in the covariant parton model approach
• Parton distribution functions and quark orbital motion
• Transversity and intrinsic motion of the constituents

Cited by in corpus (5)

• Structure of the nucleon at leading and subleading twist in the covariant parton model
• Quark-model relations among TMDs in the parton model
• Parton model description of quark and antiquark correlators and TMDs
• On the role of quark orbital angular momentum in the proton spin
• The QCD evolution of TMD in the covariant approach