The piNN vertex function is calculated within a dispersion theoretical
approach, including both pi-rho and pi-sigma intermediate states, where the
sigma meson is an abbreviation for a correlated pion pair in a relative S-wave
with isospin I=0. A strong coupling between the pi-sigma and the pi-rho states
is found. This leads to a softening of the piNN form factor. In a monopole
parameterization, a cut-off Lambda=800 MeV is obtained as compared to
Lambda=1000 MeV using pi-rho intermediate states only.Comment: 6 pages, 8 figure
