Search for the leptonic decay $D^{+}\to e^{+}\hat{I}{½}_e$

Abstract

We search for the leptonic decay $D^{+}\to e^{+}\hat{I}{½}_e$ 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 $D^{+}\to e^{+}\hat{I}{½}_e$ 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.