Dressed-quarks and the nucleon's axial charge

Understand

The nucleon's axial charge, g_A, expresses features that are both fundamental to the strong interaction and crucial to its connection with weak interaction physics.

• We show that dynamical chiral symmetry breaking (DCSB) suppresses the axial-charge of a dressed-quark, g_A^q, at infrared momenta.
• Since this effect disappears as chiral symmetry is restored, one may argue that g_A vanishes with the restoration of chiral symmetry because no nucleon bound-state survives the associated transition.
• The suppression of g_A^q is shown to be part of an explanation for a 25% reduction of g_A from its nonrelativistic quark-model value.