Neutron electric dipole moment in chiral quark-meson models.

Abstract

The neutron electric dipole moment is calculated in models of the quark structure of nucleons. The models studied incorporate chiral symmetry and the axial anomaly. The results are shown to satisfy the requirement of vanishing if either the strength of the anomaly or any current quark mass vanishes. In the cloudy-bag model both quark and pion-loop contributions to the dipole moment are found and these reinforce. In the color-dielectric model, which is consistent with partial conservation of the axial-vector current, there is only a pion-loop contribution.