Hyperon II: Properties of excited hyperons

Abstract

We report properties of $\Lambda$ and $\Sigma$ hyperon resonances formed in $K^-$ induced reactions. Special emphasis is laid on the analysis of the three-body final states $2\pi^0\Lambda$ and $2\pi^0\Sigma$ and of the quasi-two-body final states $\pi\Lambda(1520)$, $\bar K\Delta(1232)$, $\pi\Sigma(1385)$, $\bar K^*N$, and $\omega\Lambda$. We give pole positions of $\Lambda$ and $\Sigma$ hyperon resonances and transition residues from the $K^-p$ initial to various final states as well as Breit-Wigner masses and widths and decay branching ratios. Twenty resonances and "bumps" reported in the Review of Particle Physics are not required in our fits, evidence for five new resonances is reported. The observed mass spectrum is compared to the spectrum calculated in the Bonn quark model. Three spin doublets, six $\Lambda$ hyperons, are tentatively assigned to the SU(3) singlet system.