Coupled-Channel Model for $\bar{K}N$ Scattering in the Resonant Region

TL;DR

This paper develops a unitarity-preserving, multichannel model for antikaon-nucleon scattering in the resonance region, fitting extensive partial wave data to identify hyperon resonance poles and improve understanding of the $S=-1$ hyperon spectrum.

Contribution

It introduces a comprehensive, analytically consistent coupled-channel model for $ar{K}N$ scattering, fitting data up to 2.15 GeV to extract resonance poles and compare with previous analyses.

Findings

Identified $ar{K}N$ resonance poles, including $ ext{Lambda}^*$ and $ ext{Sigma}^*$ states.

Revealed significant differences with prior analyses, highlighting the need for more experimental data.

Provided the most complete hyperon spectrum analysis to date.

Abstract

We present a unitary multichannel model for $\bar{K}N$ scattering in the resonance region that fulfills unitarity. It has the correct analytical properties for the amplitudes once they are extended to the complex-$s$ plane and the partial waves have the right threshold behavior. To determine the parameters of the model, we have fitted single-energy partial waves up to $J=7/2$ and up to 2.15 GeV of energy in the center-of-mass reference frame obtaining the poles of the $\Lambda^*$ and $\Sigma^*$ resonances, which are compared to previous analyses. We provide the most comprehensive picture of the $S=-1$ hyperon spectrum to date. Important differences are found between the available analyses making the gathering of further experimental information on $\bar{K}N$ scattering mandatory to make progress in the assessment of the hyperon spectrum.