Strong coupling constant of a negative parity nucleon with a $\pi$ meson in light-cone QCD sum rules

We estimate the strong coupling constant between the negative parity nucleons with $\pi$ meson within the light-cone QCD sum rules. A method for eliminating the unwanted contributions coming from the nucleon-nucleon and nucleon–negative parity nucleon transition is presented. It is observed that the value of the strong coupling constant of the negative parity nucleon $N^{*}{N}^{*}\pi$ transition is smaller by about 50% compared to the coupling constant of the positive parity $NN\pi$ transition.

Figure 1

The dependence of the strong coupling constant $g_{N^{*}{N}^{*}\pi }$ on the Borel parameter $M^2$, at the fixed value of the continuum threshold $s_0=4.4{\mathrm{GeV}}^2$, and several fixed values of the auxliary parameter $\beta$.

Figure 2

The same as Fig. 1, but at the fixed value of the continuum threshold $s_0=4.5{\mathrm{GeV}}^2$.

Figure 3

The dependence of the strong coupling constant $g_{N^{*}{N}^{*}\pi }$ on $cos\theta$, at the fixed value of the continuum threshold $s_0=4.4{\mathrm{GeV}}^2$, at several fixed values of $M^2$.

Figure 4

The same as Fig. 3, but at the fixed value of the continuum threshold $s_0=4.5{\mathrm{GeV}}^2$.