Axial exchange currents and nucleon spin

Abstract

We calculate the hypercharge and flavor singlet axial couplings related to the spin of the nucleon in a constituent quark model. In addition to the standard one-body axial currents, the model includes two-body axial exchange currents. The latter are necessary to satisfy the Partial Conservation of Axial Current (PCAC) condition. For both axial couplings we find significant corrections to the standard quark model prediction. Exchange currents reduce the valence quark contribution to the nucleon spin and afford an interpretation of the missing nucleon spin as orbital angular momentum carried by nonvalence quark degrees of freedom.

14 pages, 1 figure

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Cited by in corpus (14)

• Axial $N\to \Delta (1232)$ and $N\to N^{\star }(1440)$ transition form factors
• Two-component model for the axial form factor of the nucleon
• Axial form factors of the octet baryons in a covariant quark model
• Axial-vector form factors for the low lying octet baryons in the chiral quark constituent model
• Quark scalar, axial, and pseudoscalar charges in the Schwinger-Dyson formalism
• Spin of ground state baryons
• Nucleon structure functions and longitudinal spin asymmetries in the chiral quark constituent model
• Axial-vector charges of the spin ${\frac{1}{2}}^{+}$ and spin ${\frac{3}{2}}^{+}$ light and charmed baryons in the SU(4) chiral quark constituent model
• Static and dynamic properties of hadronic systems with heavy quarks b and c
• Ernest Henley and the shape of baryons
• Covariant Hamiltonian Dynamics with Negative Energy States
• The quark orbital angular momentum of ground state octet baryons
• Flavor asymmetry of the nucleon sea in an unquenched quark model
• Recent developments in the constituent quark model including quark-antiquark pairs