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

Abstract

We have measured the branching fractions of the Cabibbo-suppressed decays $Λ^+_c$ $\to$ $Λ^{0}$ $K^+$ and $Λ^+_c$ $\to$ $Σ^0$ $K^+$ %(measured with improved accuracy). relative to the Cabibbo-allowed decay modes $Λ^+_c$ $\to$ $Λ^{0}$ $π^+$ and $Λ^+_c$ $\to$ $Σ^0$ $π^+$ 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 $Λ^+_c$ $\to$ $Λ^{0}$ $K^+ π^+ π^-$ and have measured the branching fraction relative to $Λ^+_c$ $\to$ $Λ^{0}$ $π^+$ to be $0.266 \pm 0.027 (\textnormal{stat.}) \pm 0.032 (\textnormal{syst.})$. The upper limit of the branching fraction into the decay $Λ^+_c$ $\to$ $Σ^0$ $K^+ π^+ π^-$ relative to $Λ^+_c$ $\to$ $Σ^0$ $π^+$ 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.

16pages, 5figures, contributed to ICHEP2004