The Gluon Spin in the Chiral Bag Model

Abstract

We study the gluon polarization contribution at the quark model renormalization scale to the proton spin, $\Gamma$, in the chiral bag model. It is evaluated by taking the expectation value of the forward matrix element of a local gluon operator in the axial gauge $A^{+}=0$. It is shown that the confining boundary condition for the color electric field plays an important role. When a solution satisfying the boundary condition for the color electric field, which is not the conventionally used but which we favor, is used, the $\Gamma$ has a positive value for {\it all} bag radii and its magnitude is comparable to the quark spin polarization. This results in a significant reduction in the relative fraction of the proton spin carried by the quark spin, which is consistent with the small flavor singlet axial current measured in the EMC experiments.

Corrections to figures

References in corpus (8)

• The theory and phenomenology of polarized deep inelastic scattering
• Status of the Proton Spin Problem
• Gluon Spin in the Nucleon
• Smooth Bosonization II: The Massive Case
• The Proton Spin in the Chiral Bag Model : Casimir Contribution and Cheshire Cat Principle
• Gluon Spin in a Quark Model
• Gluon Polarization from QCD Sum Rules
• The Proton Spin Puzzle: A Status Report

Cited by in corpus (6)

• X(1835) as the Lowest Mass Pseudoscalar Glueball and Proton Spin Problem
• Octet and Decuplet Baryon Magnetic Moments in the Chiral Quark Model
• Static properties of chiral models with SU(3) group structure
• The Spin Budget of the Proton at NNLO and Beyond
• Exploring the polarization of gluons in the nucleon
• Sum rules for strange form factors and flavor singlet axial charges