We report a search for the decay $D^0$→$e^{+}$$e^{\mathrm{-}}$ based on a data sample of 9.6 ${\mathrm{pb}}^{\mathrm{-}1}$ collected at the ψ(3770) resonance with the Mark III detector at the SLAC $e^{+}$$e^{\mathrm{-}}$ 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($D^0$→$e^{+}$$e^{-}$)<1.3×${10}^{-4}$ at the 90% confidence level. This limit constrains various extensions of the standard model.

• Received 18 December 1987

DOI:https://doi.org/10.1103/PhysRevD.37.2023