Resonance and decay of the N(1875) in triangle singularity

Speaker: Daris Samart (Khon Kaen U, Korea)
Date & time: 3 pm KST, Oct 19, 2021
Place: Online (Zoom)

In this talk, we will first briefly review the mechanism of the triangle singularity in hadronic scattering processes. Then, the resonance of the $N^∗(1875)(3/2^-)$ with a coupled-channel unitary approach is studied by considering the $\Delta\pi$ and $\Sigma^* K$, with their interaction extracted from chiral Lagrangians. In addition, two more channels, the $N^∗(1535)\pi$ and $N\sigma$ are taken into account via triangle diagrams involving the $\Sigma^* K$ and $\Delta\pi$ respectively in the intermediate states. As results, the triangle diagram in the $N^*(1535)\pi$ case develops a singularity at the same energy as the resonance mass. We determined the couplings of the resonance to the different channels and the partial decay widths. We found a very large decay width to $\Sigma^* K$ and observed that, due to interference with other terms, the Nσ channel has an important role in the ππ mass distributions at low invariant masses, leading to an apparently large $N\sigma$ decay width. Finally, we discuss justifying the convenience of an experimental reanalysis of this resonance using coupled-channel unitary schemes.

Reference:
[1] D. Samart, W. H. Liang and E. Oset, Phys. Rev. C96, 035202 (2017).