Hyperons analogous to the \Lambda(1405)

TL;DR

This paper uses the Skyrme model to analyze hyperon spectra, successfully explaining the $ ext{Lambda}(1405)$ and predicting new hyperon resonances with parity doublets and specific mass differences.

Contribution

It demonstrates that the bound state approach of the Skyrme model can account for the $ ext{Lambda}(1405)$ and predicts new hyperon resonances, including $ ext{Xi}(1620)$ and $ ext{Xi}(1690)$.

Findings

The model predicts parity doublets with ~300 MeV mass difference.

Successfully describes both $ ext{Lambda}(1116)$ and $ ext{Lambda}(1405)$.

Predicts existence of $ ext{Xi}(1620)$ and $ ext{Xi}(1690)$ with $j^P=1/2^-$.

Abstract

The low mass of the $\Lambda(1405)$ hyperon with $j^P = 1/2^-$, which is higher than the ground state $\Lambda(1116)$ mass by 290 MeV, is difficult to understand in quark models. We analyze the hyperon spectrum in the bound state approach of the Skyrme model that successfully describes both the $\Lambda(1116)$ and the $\Lambda(1405)$. This model predicts that several hyperon resonances of the same spin but with opposite parity form parity doublets that have a mass difference of around 300 MeV, which is indeed realized in the observed hyperon spectrum. Furthermore, the existence of the $\Xi(1620)$ and the $\Xi(1690)$ of $j^P=1/2^-$ is predicted by this model. Comments on the $\Omega$ baryons and heavy quark baryons are made as well.