Low energy reactions $K^{-}p\to {\Sigma }^0{\pi }^0$, $\Lambda {\pi }^0$, ${\bar{K}}^{0}n$ and the strangeness $S=-1$ hyperons

Abstract

A combined study of the reactions $K^{-}p\to {\Sigma }^0{\pi }^0$, $\Lambda {\pi }^0$ and ${\bar{K}}^{0}n$ at low energies is carried out with a chiral quark-model approach. Good descriptions of the experimental observations are obtained. The roles of the low-lying strangeness $S=-1$ hyperon resonances in these processes are carefully analyzed. We find that: (i) In the $K^{-}p\to {\Sigma }^0{\pi }^0$ process, both $\Lambda (1405)S_{01}$ and $\Lambda (1520)D_{03}$ play dominant roles. Significant contributions of $\Lambda (1670)S_{01}$ and $\Lambda (1690)D_{03}$ could be seen around their threshold; (ii) In the $K^{-}p\to \Lambda {\pi }^0$ process, some obvious evidence of $\Sigma (1775)D_{15}$ and $\Sigma (1750)S_{11}$ could be found. Some hints of $\Sigma (1620)S_{11}$ might exist in the reaction as well. $\Sigma (1750)S_{11}$ and $\Sigma (1620)S_{11}$ should correspond to the representations $[70{,}^{4}8]S_{11}$ and $[70{,}^{2}8]S_{11}$, respectively; (iii) In the $K^{-}p\to {\bar{K}}^{0}n$ process, the dominant resonances are $\Lambda (1405)$ and $\Lambda (1520)$. Some evidence of $\Lambda (1690)D_{03}$, $\Sigma (1670)D_{13}$ and $\Sigma (1775)D_{15}$ could be seen as well. A weak coupling of $\Lambda (1670)S_{01}$ to $\bar{K}N$ should be needed in the reactions $K^{-}p\to {\Sigma }^0{\pi }^0$ and ${\bar{K}}^{0}n$. Furthermore, by analyzing these reactions, we also find that the $u$-, t-channel backgrounds and s-channel Born term play crucial roles in the reactions.

Comments: 17 pages, 12 figures. To be published in PRC