Search for the leptonic decay $D^{+}\to e^{+}{\nu }_e$

We search for the leptonic decay $D^{+}\to e^{+}{\nu }_e$ using an $e^{+}{e}^{-}$ collision data sample with an integrated luminosity of 20.3~fb${}^{-1}$ collected with the BESIII detector at the center-of-mass energy of 3.773~GeV. No significant signal is observed and an upper limit on the branching fraction of $D^{+}\to e^{+}{\nu }_e$ is set as $9.7\times {10}^{-7}$, at the 90% confidence level. Our upper limit is an order of magnitude smaller than the previous limit for this decay mode.