Quark scalar, axial, and pseudoscalar charges in the Schwinger-Dyson formalism

Understand

We calculate the scalar, axial, and pseudoscalar charges of the quark in the Schwinger-Dyson formalism of Landau gauge QCD.

• It is found that the dressed quark scalar density of the valence quark is significantly enhanced against the bare quark contribution, and the result explains qualitatively the phenomenologically known value of the pion-nucleon sigma term and also that given by lattice QCD.
• Moreover, we show that the Richardson's interquark potential suppresses the quark scalar density in the Higashjima-Miransky approximation.
• This fact suggests that the quark scalar density is an observable that is sensitive to quark confinement.