On the strong coupling $N^{(*)}N^{(*)}\pi$

We study the strong vertices $N^*N\pi$, $N^*N^*\pi$ and $NN\pi$ in QCD, where $N^*$ denotes the negative parity $N (1535)$ state. We use the most general form of the interpolating currents to calculate the corresponding strong coupling constants. It is obtained that the coupling associated to $N^*N\pi$ vertex is strongly suppressed compared to those related to two other vertices. The strong coupling corresponding to $N^*N^*\pi$ is obtained to be roughly half of that of $NN\pi$ vertex. We compare the obtained results on $N^*N\pi$ and $NN\pi$ vertices with the existing predictions of other theoretical studies as well as those extracted from the experimental data.