Observation of ${\Lambda }_c^{+}\to {\Lambda }^0{K}^{+}$, ${\Lambda }_c^{+}\to {\Sigma }^0{K}^{+}$ and ${\Lambda }_c^{+}\to {\Sigma }^{+}{K}^{+}{\pi }^{-}$ decays

Abstract

We present measurements of the Cabibbo-suppressed decays ${\Lambda }_c^{+}\to {\Lambda }^0{K}^{+}$ and ${\Lambda }_c^{+}\to {\Sigma }^0{K}^{+}$ (both first observations), ${\Lambda }_c^{+}\to {\Sigma }^{+}{K}^{+}{\pi }^{-}$ (seen with large statistics for the first time), ${\Lambda }_c^{+}\to p{K}^{+}{K}^{-}$ and ${\Lambda }_c^{+}\to p\varphi$ (measured with improved accuracy). Improved branching ratio measurements for the decays ${\Lambda }_c^{+}\to {\Sigma }^0{K}^{+}{K}^{-}$ and ${\Lambda }_c^{+}\to {\Sigma }^0\varphi$, which are attributed to W-exchange diagrams, are shown. We also present the first evidence for ${\Lambda }_c^{+}\to \Xi (1690)K^{+}$ and set an upper limit on non-resonant ${\Lambda }_c^{+}\to {\Sigma }^0{K}^{+}{K}^{-}$ decay. This analysis was performed using 23.6 fb${}^{-1}$ of data collected by the Belle detector at the $e^{+}{e}^{-}$ asymmetric collider KEKB.

Paper submitted to the 2001 Lepton Photon Conference