Search for the Decayd0→e+

We report a search for the decay ${D}^{0}$\ensuremath{\rightarrow}${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$ based on a data sample of 9.6 ${\mathrm{pb}}^{\mathrm{\ensuremath{-}}1}$ collected at the \ensuremath{\psi}(3770) resonance with the Mark III detector at the SLAC ${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$ storage ring SPEAR. We find no evidence for this flavor-changing weak-neutral-current decay and set an upper limit on the branching ratio of B(${D}^{0}$\ensuremath{\rightarrow}${e}^{+}$${e}^{\ensuremath{-}}$)1.3\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}4}$ at the 90% confidence level. This limit constrains various extensions of the standard model.