Role of a triangle singularity in the $πΔ$ decay of the $N(1700)(3/2^-)$

Abstract

We show the important role played by the $πΔ(1232)$ channel in the build up of the $N(1700)(3/2^-)$ resonance due to the non-trivial enhancement produced by a singularity of a triangular loop. The $N(1700)$ is one of the dynamically generated resonances produced by the coupled channel vector-baryon interaction. The $πΔ$ channel was neglected in previous works but we show that it has to be incorporated into the coupled channel formalism due to an enhancement produced by a singularity in the triangular loop with $ρ$, nucleon and $π$ as internal loop lines and $π$ and $Δ$ as external ones. The enhancement is of non-resonant origin but it contributes to the dynamical generation of the $N(1700)$ resonance due to the non-linear dynamics involved in the coupled channel mechanisms. We obtain an important increase of the total width of the $N(1700)$ resonance when the $πΔ$ channel is included and provide predictions for the partial widths of the $N(1700)$ decays into $VB$ and $πΔ$.