  We have calculated coupling constants of a neutral pion with the lowest two
nucleon resonances. This includes both the diagonal as well as non-diagonal
coupling constant involving a nucleon resonance and a nucleon. For this, we
first calculate vacuum-to-pion correlation function of the interpolating fields
of two nucleons and then take its matrix elements with respect to nucleon
and/or nucleon resonance spinors. Using different QCD sum rules obtained from
different matrix elements we eliminate unwanted coupling constants and solve
for the desired ones.16
