Contact-interaction Faddeev equation and, inter alia, proton tensor charges
Shu-Sheng Xu🇨🇳 · Chen Chen🇨🇳 · Ian C.Cloet🇺🇸 · Craig D. Roberts🇺🇸 · Jorge Segovia🇪🇸 · Hong-Shi Zong🇨🇳
A confining, symmetry-preserving, Dyson-Schwinger equation treatment of a vector-vector contact interaction is used to formulate Faddeev equations for the nucleon and Delta-baryon in which the kernel involves dynamical dressed-quark exchange and whose solutions therefore provide momentum-dependent Faddeev amplitudes. These solutions are compared with those obtained in the static approximation and with a QCD-kindred formulation of the Faddeev kernel. They are also used to compute a range of nucleon properties, amongst them: the proton's sigma-term; the large Bjorken-x values of separate ratios of unpolarised and longitudinally-polarised valence u- and d-quark parton distribution functions; and the proton's tensor charges, which enable one to directly determine the effect of dressed-quark electric dipole moments (EDMs) on neutron and proton EDMs.