Spin structure of the nucleon: QCD evolution, lattice results and models

Abstract

The question how the spin of the nucleon is distributed among its quark and gluon constituents is still a subject of intense investigations. Lattice QCD has progressed to provide information about spin fractions and orbital angular momentum contributions for up- and down-quarks in the proton, at a typical scale μ^2~4 GeV^2. On the other hand, chiral quark models have traditionally been used for orientation at low momentum scales. In the comparison of such model calculations with experiment or lattice QCD, fixing the model scale and the treatment of scale evolution are essential. In this paper, we present a refined model calculation and a QCD evolution of lattice results up to next-to-next-to-leading order. We compare this approach with the Myhrer-Thomas scenario for resolving the proton spin puzzle.

11 pages, 6 figures, equation (9) has been corrected leading to a revised figure 1b. Revision matches published version

References in corpus (16)

• Extraction of Spin-Dependent Parton Densities and Their Uncertainties
• The Deuteron Spin-dependent Structure Function g1d and its First Moment
• Nucleon structure from mixed action calculations using 2+1 flavors of asqtad sea and domain wall valence fermions
• QCD Analysis of the Polarized World Data
• Hadron structure from lattice quantum chromodynamics
• QCD Analysis of Polarized Deep Inelastic Scattering Data
• On the running coupling constant in QCD
• Interplay of Spin and Orbital Angular Momentum in the Proton
• On Gauge-Invariant Decomposition of Nucleon Spin
• Chiral Perturbation Theory and the first moments of the Generalized Parton Distriputions in a Nucleon
• Resolution of the Proton Spin Problem
• The nucleon's octet axial-charge g_A^8 with chiral corrections
• Towards the NNLO evolution of polarised parton distributions
• Gluon Polarisation in the Nucleon and Longitudinal Double Spin Asymmetries from Open Charm Muoproduction
• Phenomenological analysis of the nucleon spin contents and their scale dependence
• Spin and orbital angular momentum of the proton

Cited by in corpus (6)

• The quark orbital angular momentum from Wigner distributions and light-cone wave functions
• The Spin Structure of the Nucleon
• The Spin Budget of the Proton at NNLO and Beyond
• Octet Spin Fractions and the Proton Spin Problem
• Twist-four gravitational form factor at NNLO QCD from trace anomaly constraints
• The role of the GPD E in the determination of the parton angular momenta