Nucleons with chiral loops

This article extends the analysis of the low-energy structure of Green functions in QCD to processes with one external nucleon. We calculate various nucleon matrix elements of quark currents and determine the elastic πN scattering amplitude T_πN for off-shell pions to one loop. As an application of our representation of T_πN we evaluate the difference Δ_R between the amplitude overlineD at the Cheng-Dashen point and the scalar form factor σ(2 M_π²). The obtained result is a factor of 50 too small to explain the difference between the value of σ extracted from elastic πN scattering and the value obtained from the baryon mass spectrum.