Improved upper limit on flavor-changing neutral-current decays of the<i>b</i>quark

We report the results of a new search for flavor-changing neutral-current decays of the b quark and present a 90%-confidence-level upper limit for the branching fraction for B\ensuremath{\rightarrow}${l}^{+}$${l}^{\mathrm{\ensuremath{-}}}$X of 1.2\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}3}$.