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

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 $\Xi (1620{)}^0$.