$\bar{K}\Lambda$ molecular explanation to the newly observed $\Xi (1620{)}^0$

Abstract

The newly observed $\Xi (1620{)}^0$ by the Belle Collaboration inspires our interest in performing a systematic study on the interaction of an anti-strange meson $({\bar{K}}^{(\ast )})$ with a strange or doubly strange ground octet baryon $\mathcal{B}$ ($\Lambda$, $\Sigma$, and $\Xi$), where the spin-orbit force and the recoil correction are considered in the adopted one-boson-exchange model. Our results indicate that $\Xi (1620{)}^0$ can be explained as a $\bar{K}\Lambda$ molecular state with $I(J^P)=1/2(1/2^{-})$ and the intermediate force from $\sigma$ exchange plays an important role. Additionally, we also predict several other possible molecular candidates, i.e., the $\bar{K}\Sigma$ molecular state with $I(J^P)=1/2(1/2^{-})$ and the triply strange $\bar{K}\Xi$ molecular state with $I(J^P)=0(1/2^{-})$.

Comments: 7 pages, 5 figures, and 4 tables