The pseudoscalar meson and baryon octet interaction with strangeness $S=-2$ in the unitary coupled-channel approximation

TL;DR

This paper investigates pseudoscalar meson and baryon octet interactions with strangeness S=-2 using the Bethe-Salpeter equation, revealing a dynamically generated resonance around 1550MeV with a broad decay width, and studying its finite-volume energy levels.

Contribution

It introduces a detailed analysis of the S=-2 meson-baryon interaction using the coupled-channel approach in both infinite and finite volumes, identifying a new resonance state.

Findings

A resonance at about 1550MeV with a large decay width of 120-200MeV.

The resonance couples strongly to the πΞ channel.

An energy level at 1570MeV in finite volume, between the πΞ and K̄Λ thresholds.

Abstract

The interaction of the pseudoscalar meson and the baryon octet is investigated by solving the Bethe-Salpeter equation in the infinite and finite volume respectively. It is found that there is a resonance state generated dynamically, which owns a mass about 1550MeV and a large decay width of 120-200MeV. This resonance state couples strongly to the $\pi \Xi$ channel. Therefore, it might not correspond to the $\Xi(1620)$ particle announced by Belle collaboration. At the same time, this problem is studied in the finite volume, and an energy level at 1570MeV is obtained, which is between the $\pi \Xi$ and $\bar{K}\Lambda$ thresholds and independent of the cubic box size.