Search for the rare decay $D^+ to D^0 e^+ u_e$

We search for the rare decay $D^+to D^0 e^+ u_{e}$, using a data set with an integrated luminosity of 2.93 $rm fb^{-1}$ collected at $sqrt{s}=3.773$ GeV with the BESIII detector operating at the BEPCII storage rings. No signals are observed. We set the upper limit on the branching fraction for $D^+to D^0 e^+ u_e$ to be $1.0times 10^{-4}$ at the 90% confidence level.