Strong decays of the $\Xi(1620)$ as a $\Lambda\bar{K}$ and $\Sigma\bar{K}$ molecule

TL;DR

This paper investigates the strong decay mechanisms of the $ ext{Xi}(1620)$ resonance, proposing it as a meson-baryon molecule, and finds that the decay data supports a specific spin-parity assignment, enhancing understanding of its nature.

Contribution

It introduces a molecular state model for $ ext{Xi}(1620)$ and evaluates decay widths for different spin-parity assignments, favoring $1/2^-$ based on experimental data.

Findings

Decay width favors $1/2^-$ assignment.

Approximately 52-68% of decay width from $ar{K} ext{-} ext{Lambda}$ channel.

Both $ar{K} ext{-} ext{Lambda}$ and $ar{K} ext{-} ext{Sigma}$ channels are significant.

Abstract

In this work, we study the strong decays of the newly observed $\Xi(1620)^0$ assuming that it is a meson-baryon molecular state of $\Lambda\bar{K}$ and $\Sigma\bar{K}$. We consider four possible spin-parity assignments $J^P=1/2^{\pm}$ and $3/2^{\pm}$ for the $\Xi(1620)^0$, and evaluate its partial decay width into $\Xi\pi$ via hadronic loops with the help of effective Lagrangians. In comparison with the Belle data, the calculated decay width favors the spin-party assignment $1/2^-$ while the other spin-parity assignments do not yield a decay width consistent with data in the molecule picture. We find that about $52\%$-$68\%$ of the total width comes from the $\bar{K}\Lambda$ channel, while the rest is provided by the $\bar{K}\Sigma$ channel. As a result, both channels are important in explaining the strong decay of the $\Xi(1620)^0$. This information is helpful to further understand the nature of the $\Xi(1620)^0$.