Axial exchange currents and the spin content of the nucleon
Abstract
In a chiral quark model where chiral symmetry is introduced via a non-linear sigma model, we evaluate the axial couplings g_A(0), g_A^8(0) and g_A^0(0 )related to the spin structure of the nucleon. Our calculation includes one-body and two-body axial current and pion absorption operators, which satisfy the Partial Conservation of Axial Current (PCAC) condition. While g_A(0) is dominated by the one-body axial current we find significant corrections due to two-body axial exchange currents in g_A^8(0) and g_A^0(0). Interestingly, the axial current associated with gluon exchange reduces g_A^8(0) from 1 to 0.6. Our analysis shows that the so-called ``proton spin crisis'' can be resolved in a constituent quark model in which PCAC is satisfied. Furthermore, we use the PCAC constraint in order to determine the couplings of the eta and eta' mesons to nucleons.
Keywords
Cite
@article{arxiv.nucl-th/0303020,
title = {Axial exchange currents and the spin content of the nucleon},
author = {D. Barquilla-Cano and A. J. Buchmann and E. Hernandez},
journal= {arXiv preprint arXiv:nucl-th/0303020},
year = {2007}
}
Comments
30 pages, 3 figures