Ξ−Production in 5.5-GeV/cK−pInteractions

Final states with a ${\Xi }^{-}$ hyperon have been studied in 5.5-GeV/c $K^{-}p$ interactions. Center-of-mass production angular distributions for the ${\Xi }^{-}$ have a peak in the beam direction, while those for the $K^{+}$ or $K^0$ meson peak in the opposite direction. Approximately half of the observed events involve the ${\Xi }^{*}\mathrm{}\left(1530\right)\mathrm{}$ or $K^{*}\mathrm{}\left(890\right)\mathrm{}$ resonances. The four- and five-body final states show production of the ${\Xi }^{*}\mathrm{}\left(1930\right)\mathrm{}$ in the ${\Xi }^{-}{\pi }^{+,0\mathrm{}}$ mass spectrum and a narrow peak at 2295 MeV in the ${\Xi }^{-}{\pi }^{+}{\pi }^{-}$ mass spectrum. The mass of the ${\Xi }^{-}$ hyperon is 1321.9±0.5 MeV as determined from 195 ${\Xi }^{-}$ decays with a visible $\Lambda$ decay, assuming a $\Lambda$-hyperon mass of 1115.58 MeV.