Ghost poles in the nucleon propagator in the linear-sigma model approach and its role in pion-nucleon low-energy theorems

C. A. da Rocha, G. Krein, L. Wilets

Complex mass poles, or ghost poles, are present in the Hartree-Fock solution of the Schwinger-Dyson equation for the nucleon propagator in renormalizable models with Yukawa-type me…