First Observation of $D^{0(+)}\to \bar{K}\ddot{I}‰e^{+}\hat{I}{½}_e$ and Determination of the Branching Fraction of ${\bar{K}}_1(1270)\to \bar{K}\ddot{I}‰$

BESIII Collaboration, M. Ablikim, M. N. Achasov +685

Using 20.3~fb${}^{-1}$ of $e^{+}{e}^{-}$ annihilation data collected at a center-of-mass energy of 3.773~GeV with the BESIII detector, we report the first observation of the semileptonic d…