Observation of Semileptonic Decays of Charmed Baryons

Abstract

Direct electrons are observed in baryon events produced in ${e}^{+}{e}^{\ensuremath{-}}$ annihilation at center-of-mass energies above the ${\ensuremath{\Lambda}}_{c}{\overline{\ensuremath{\Lambda}}}_{c}$ threshold. These events are attributed to charmed-baryon pair production and subsequent ${\ensuremath{\Lambda}}_{c}$ semileptonic decay. Various semileptonic branching ratios of the ${\ensuremath{\Lambda}}_{c}$ are determined, including $B({\ensuremath{\Lambda}}_{c}\ensuremath{\rightarrow}{e}^{+}X)=(4.5\ifmmode\pm\else\textpm\fi{}1.7)%$.