Establishing mass spectrum of $S=-1$ hyperon resonances via a dynamical coupled-channels analysis of $K^-p$ reactions

TL;DR

This study performs a detailed coupled-channels analysis of K^- p reactions to extract hyperon resonance parameters, revealing a potential new narrow Lambda resonance near the eta Lambda threshold and providing insights into known Lambda states.

Contribution

It introduces a comprehensive dynamical coupled-channels approach to determine hyperon resonance parameters from experimental data, suggesting the existence of a new narrow Lambda resonance.

Findings

Identification of a possible new narrow J^P=3/2^+ Lambda resonance at 1671 MeV

Extraction of pole positions for Lambda(1405) and other Lambda resonances

Data favor the existence of the proposed new Lambda resonance near the eta Lambda threshold

Abstract

We report our recent effort for the extraction of resonance parameters (complex pole mass and residues etc.) associated with Lambda* and Sigma* hyperons. This was accomplished via a comprehensive partial-wave analysis of the data for K^- p --> barK N, pi Sigma, pi Lambda, eta Lambda, K Xi reactions from the thresholds up to W=2.1 GeV within a dynamical coupled-channels approach. The results suggest a possible existence of new narrow J^P=3/2^+ \Lambda resonance with pole mass 1671^{+2}_{-8} -i(5^{+11}_{-2}) MeV, located close to the eta Lambda threshold. This resonance is found to be responsible for reproducing the data for K^-p --> eta Lambda differential cross sections near the threshold, and thus the data seem favor its existence. The extracted poles for J^P=1/2^- Lambda resonances below the barK N threshold, including Lambda(1405), are also presented.