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

In this work, we study the strong decays of the newly observed $\varXi (1620)^0$ assuming that it is a meson-baryon molecular state of $\varLambda {\bar{K}}$ and $\varSigma {\bar{K}}$. We consider four possible spin-parity assignments $J^P=1/2^{\pm }$ and $3/2^{\pm }$ for the $\varXi (1620)^0$, and evaluate its partial decay width into $\varXi \pi $ and $\varXi \pi \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}}\varLambda $ channel, while the rest is provided by the ${\bar{K}}\varSigma $ channel. As a result, both channels are important in explaining the strong decay of the $\varXi (1620)^0$. In addition, the transition $\varXi (1620)^0\rightarrow \pi \varXi $ is the main decay channel in the $J^{P}=1/2^{-}$ case, which almost saturates the total width. These information are helpful to further understand the nature of the $\varXi (1620)^0$.