Observation of the Semileptonic Decay $D^0\to a_0(980{)}^{-}{e}^{+}\hat{I}{½}_e$ and Evidence for $D^{+}\to a_0(980{)}^0{e}^{+}\hat{I}{½}_e$

Abstract

Using an $e^{+}{e}^{-}$ collision data sample of 2.93 fb${}^{-1}$ collected at a center-of-mass energy of 3.773 GeV by the BESIII detector at BEPCII, we report the observation of $D^0\to a_0(980{)}^{-}{e}^{+}\hat{I}{½}_e$ and evidence for $D^{+}\to a_0(980{)}^0{e}^{+}\hat{I}{½}_e$ with significances of $6.4\ddot{I}ƒ$ and $2.9\ddot{I}ƒ$, respectively. The absolute branching fractions are determined to be $\mathcal{B}(D^0\to a_0(980{)}^{-}{e}^{+}\hat{I}{½}_e)\times \mathcal{B}(a_0(980{)}^{-}\to \hat{I}\cdot \ddot{I}{€}^{-})=(1.33_{-0.29}^{+0.33}(\mathrm{stat})\pm 0.09(\mathrm{syst}))\times 10^{-4}$ and $\mathcal{B}(D^{+}\to a_0(980{)}^0{e}^{+}\hat{I}{½}_e)\times \mathcal{B}(a_0(980{)}^0\to \hat{I}\cdot \ddot{I}{€}^0)=(1.66_{-0.66}^{+0.81}(\mathrm{stat})\pm 0.11(\mathrm{syst}))\times 10^{-4}$. An upper limit of $\mathcal{B}(D^{+}\to a_0(980{)}^0{e}^{+}\hat{I}{½}_e)\times \mathcal{B}(a_0(980{)}^0\to \hat{I}\cdot \ddot{I}{€}^0)<3.0\times 10^{-4}$ is also determined at the $90\%$ confidence level.