Study ofK−p→Σππin the Region of theΛ(1520)

Abstract

The reactions $K^{-}p\to {\Sigma }^{+}{\pi }^{-}{\pi }^0, {\Sigma }^{-}{\pi }^{+}{\pi }^0, \mathrm{and} {\Sigma }^0{\pi }^{+}{\pi }^{-}$ have been analyzed in the region of the $\Lambda \mathrm{}\left(1520\right)\mathrm{}$. The data are consistent with the dominance of the reaction sequence $K^{-}p\to \Lambda \mathrm{}\left(1520\right)\mathrm{}\to \Sigma \mathrm{}\left(1385\right)\mathrm{}\pi \to \Sigma \pi \pi$. The same sequence of resonance production and decay has been previously found to lead to the $\Lambda \pi \pi$ final state. Fits to the cross sections yield branching fractions for $\Lambda \mathrm{}\left(1520\right)\mathrm{}\to {\Sigma }^{+}{\pi }^{-}{\pi }^0, {\Sigma }^{-}{\pi }^{+}{\pi }^0, \mathrm{and} {\Sigma }^0{\pi }^{+}{\pi }^{-}$ of 0.0034 ± 0.0004, 0.0024 ± 0.0003, and 0.0027 ± 0.0003, respectively. A comparison of the $\Sigma \pi \pi$ and $\Lambda \pi \pi$ cross sections yields a branching ratio $\frac{\Gamma \left[\Sigma \mathrm{}\right(1385)\mathrm{}\to \Sigma \pi ]}{\Gamma \left[\Sigma \mathrm{}\right(1385)\mathrm{}\to \Lambda \pi ]}=0.18\mathrm{}\pm 0.04$.