Measurement of the product branching fractionB(c→ΘcX)×B(Θc→ΛX)

Abstract

Based on a high statistics ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}c\overline{c}$ data sample, we report on the inclusive rate for charmed baryons to decay into $\ensuremath{\Lambda}$ particles using charm-event tagging. We select ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}c\overline{c}$ events which have a clear anti-charm tag and measure the $\ensuremath{\Lambda}$ content in the hemisphere opposite the tag (charge conjugate modes are implicit). This allows us to determine the product branching fraction ${\mathcal{B}}_{\ensuremath{\Lambda}}=\mathcal{B}(\stackrel{\ensuremath{\rightarrow}}{c}{\ensuremath{\Theta}}_{c}X)\ifmmode\times\else\texttimes\fi{}\mathcal{B}({\ensuremath{\Theta}}_{c}\ensuremath{\rightarrow}\ensuremath{\Lambda}X),$ where ${\ensuremath{\Theta}}_{c}$ represents a sum over all charmed baryons produced in ${e}^{+}{e}^{\ensuremath{-}}$ fragmentation at $\sqrt{s}=10.5$ GeV, given our specific tags. We obtain ${\mathcal{B}}_{\ensuremath{\Lambda}}=(1.87\ifmmode\pm\else\textpm\fi{}0.03\ifmmode\pm\else\textpm\fi{}0.33)%.$

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