Measurements of ${\Lambda }_c^{+}$ Branching Fractions of Cabibbo-Suppressed Decay Modes involving $\Lambda$ and ${\Sigma }^0$

Abstract

We measure the branching ratios of the Cabibbo-suppressed decays ${\Lambda }_c^{+}$ $\to$ $\Lambda$ $K^{+}$ and ${\Lambda }_c^{+}$ $\to$ ${\Sigma }^0$ $K^{+}$ %(measured with improved accuracy). relative to the Cabibbo-favored decay modes ${\Lambda }_c^{+}$ $\to$ $\Lambda$ ${\pi }^{+}$ and ${\Lambda }_c^{+}$ $\to$ ${\Sigma }^0$ ${\pi }^{+}$ to be $0.044\pm 0.004(\text{stat.})\pm 0.003(\text{syst.})$ and $0.039\pm 0.005(\text{stat.})\pm 0.003(\text{syst.})$, respectively. We set an upper limit on the branching ratio at 90 % confidence level for ${\Lambda }_c^{+}$ $\to$ $\Lambda$ $K^{+}{\pi }^{+}{\pi }^{-}$ to be $4.1\times 10^{-2}$ relative to ${\Lambda }_c^{+}$ $\to$ $\Lambda$ ${\pi }^{+}$ and for ${\Lambda }_c^{+}$ $\to$ ${\Sigma }^0$ $K^{+}{\pi }^{+}{\pi }^{-}$ to be $2.0\times 10^{-2}$ relative to ${\Lambda }_c^{+}$ $\to$ ${\Sigma }^0$ ${\pi }^{+}$. We also measure the branching fraction for the Cabibbo-favored mode ${\Lambda }_c^{+}$ $\to$ ${\Sigma }^0$ ${\pi }^{+}$ relative to ${\Lambda }_c^{+}$ $\to$ $\Lambda$ ${\pi }^{+}$ to be $0.977\pm 0.015(\text{stat.})\pm 0.051(\text{syst.})$. This analysis was performed using a data sample with an integrated luminosity of 125 fb${}^{-1}$ collected by the $BABAR$ detector at the PEP-II asymmetric-energy $B$ factory at SLAC.

10 pages, 10 postscript figures, Published in Physics Review 75.052002