Hyperon I: Study of the $\Lambda (1405)$

Abstract

Low-energy data on the three charge states in $\gamma p\to K^{+}(\Sigma \pi )$ from CLAS at JLab, on $K^{-}p\to {\pi }^0{\pi }^0\Lambda$ and ${\pi }^0{\pi }^0\Sigma$ from the Crystal Ball at BNL, bubble chamber data on $K^{-}p\to {\pi }^{-}{\pi }^{+}{\pi }^{\pm }{\Sigma }^{\mp }$, low-energy total cross sections on $K^{-}$ induced reactions, and data on the $K^{-}p$ atom are fitted with the BnGa partial-wave-analysis program. We find that the data can be fitted well with just one isoscalar spin-1/2 negative-parity pole, the $\Lambda (1405)$, and background contributions.

9 pages, 10 figures