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

## TL;DR

This paper proposes that the newly observed $ ext{Xi}(1620)^0$ can be understood as a $ar{K} ext{Lambda}$ molecular state, using a one-boson-exchange model considering spin-orbit and recoil effects, and predicts additional molecular candidates.

## Contribution

It provides a molecular explanation for $ ext{Xi}(1620)^0$ and predicts new possible molecular states involving anti-strange mesons and strange baryons.

## Key findings

- $ ext{Xi}(1620)^0$ is explained as a $ar{K} ext{Lambda}$ molecular state.
- Intermediate $ ext{sigma}$ exchange is crucial for binding.
- Predicted additional molecular candidates: $ar{K} ext{Sigma}$ and $ar{K} ext{Xi}$ states.

## 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 $(\bar{K}^{(*)})$ 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 $I(J^P)=0(1/2^-)$.