Measurements of $\Lambda^+_c$ Branching Fractions of Cabibbo-Suppressed Decay Modes

Abstract

We have measured the branching fractions of the Cabibbo-suppressed decays $\Lambda^+_c$ $\to$ $\Lambda^{0}$ $K^+$ and $\Lambda^+_c$ $\to$ $\Sigma^0$ $K^+$ %(measured with improved accuracy). relative to the Cabibbo-allowed decay modes $\Lambda^+_c$ $\to$ $\Lambda^{0}$ $\pi^+$ and $\Lambda^+_c$ $\to$ $\Sigma^0$ $\pi^+$ to be $ 0.044 \pm 0.004 (\textnormal{stat.}) \pm 0.002 (\textnormal{syst.})$ and $ 0.040 \pm 0.005 (\textnormal{stat.}) \pm 0.004 (\textnormal{syst.})$, respectively. We also present the first observation of $\Lambda^+_c$ $\to$ $\Lambda^{0}$ $K^+ \pi^+ \pi^-$ and have measured the branching fraction relative to $\Lambda^+_c$ $\to$ $\Lambda^{0}$ $\pi^+$ to be $0.266 \pm 0.027 (\textnormal{stat.}) \pm 0.032 (\textnormal{syst.})$. The upper limit of the branching fraction into the decay $\Lambda^+_c$ $\to$ $\Sigma^0$ $K^+ \pi^+ \pi^-$ relative to $\Lambda^+_c$ $\to$ $\Sigma^0$ $\pi^+$ has been measured to be %7.6 \times 10^{-4}$ $ < 3.9 \times 10^{-2}$ at the 90% confidence level. This analysis was performed using a data sample of %approximately 125 fb$^{-1}$ (integrated luminosity) collected by the \babar$ $detector at the PEP-II asymmetric-energy $B$ Factory at the Stanford Linear Accelerator Center. All results presented in this conference contribution are preliminary.