Studying the $\Xi (2030)$ as a predominantly ${\bar{K}}^{\ast }\Sigma$ molecular state

Abstract

Since its discovery in 1977, the spin-parity of $\Xi (2030)$ has not been fully determined experimentally. The latest Particle Data Group (PDG) listing suggests it may be a baryon with $J=5/2$. Therefore, studying the mass spectrum and decay properties of $\Xi (2030)$ has become a current hot topic to definitively establish its spin-parity. As the three-quark model fails to explain $\Xi (2030)$, we previously proposed it may be a molecule primarily composed of ${\bar{K}}^{}\Sigma$ with $J^P=5/2^{+}$, based on its mass spectrum study. To verify its molecular state interpretation, this work proposes studying the strong decays of $\Xi (2030)$ assuming it is a $P$-wave $J^P=5/2^{+}$ meson-baryon molecule predominantly composed of ${\bar{K}}^{}\Sigma$. We calculated all experimentally measured two-body and three-body final state decay widths of $\Xi (2030)$, including $\Xi (2030)\to \bar{K}\Lambda ,\bar{K}\Sigma ,\pi \Xi ,\pi {\Xi }^{\ast }$, and $\Xi (2030)\to \pi \pi \Xi ,\pi \bar{K}\Sigma ,\pi \bar{K}\Lambda$. The results indicate that both the total decay width and partial decay widths agree well with experimental values within the error margins. This supports that $\Xi (2030)$ is a molecule with spin-parity $J^P=5/2^{+}$, predominantly composed of ${\bar{K}}^{\ast }\Sigma$. Compared to the experimental central values, our results are slightly smaller, which suggests that $\Xi (2030)$ may contain additional components besides meson-baryon molecular components, such as three quark structures.

Comments: 8 papers,6 figures,1 table