Nature of excited $\Xi$ baryons with threshold effects

TL;DR

This paper investigates the nature of the excited $ ext{Xi}$ baryon $ ext{Xi}(1620)$ near the $ar{K} ext{Lambda}$ threshold, showing threshold effects significantly influence its observed resonance shape.

Contribution

The study introduces a coupled-channels meson-baryon scattering model to account for threshold effects on the $ ext{Xi}(1620)$ resonance, providing a more accurate description of its spectral features.

Findings

Threshold effects distort the $ ext{Xi}(1620)$ resonance peak.

Coupled-channels analysis reveals the resonance's nature near the threshold.

The resonance shape deviates from a simple Breit-Wigner distribution.

Abstract

Spectroscopy of excited baryons with strangeness $S=-2$ is stimulated by recent experimental developments. Here we focus on the $\Xi(1620)$ which locates close to the $\bar{K}\Lambda$ threshold. To take into account the threshold effects, we construct the coupled-channels meson-baryon scattering amplitude where the $\Xi(1620)$ appears as a resonance. We demonstrate that the $\bar{K}\Lambda$ threshold effects distort the peak of the $\Xi(1620)$ resonance from the simple Breit-Wigner distribution.