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

Abstract

A combined study of the reactions $K^-p\rightarrow \Sigma^0\pi^0$, $\Lambda\pi^0$ and $\bar{K}^0n$ 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 $K^-p\rightarrow \Sigma^0\pi^0$ 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 $K^-p\rightarrow \Lambda\pi^0$ 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 $[70,^48]S_{11}$ and $[70,^28]S_{11}$, respectively; (iii) In the $K^-p\rightarrow \bar{K}^0n$ 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 $K^-p\rightarrow \Sigma^0\pi^0$ and $\bar{K}^0n$. 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.