Observation of the Decay B^{-} \rightarrow D_{s}^{(*)+} K^{-} \ell^{-} \barν_{\ell}

The BABAR Collaboration, P. del Amo Sanchez

We report the observation of the decay $B^{-}\to D_s^{(\ast )+}{K}^{-}{\ell }^{-}{\bar{\nu }}_{\ell }$ based on $342 \mathrm {\,fb}^{-1}}$ of data collected at the $\Y4S$ resonance wi…