Study of the decay $D^0\to {\bar{K}}^0{\pi }^{-}{e}^{+}{\nu }_e$

Abstract

We report a study of the decay $D^0\to {\bar{K}}^0{\pi }^{-}{e}^{+}{\nu }_e$ based on a sample of $2.93{\mathrm{fb}}^{-1}$ $e^{+}{e}^{-}$ annihilation data collected at the center-of-mass energy of 3.773~GeV with the BESIII detector at the BEPCII collider. The total branching fraction is determined to be $\mathcal{B}(D^0\to {\bar{K}}^0{\pi }^{-}{e}^{+}{\nu }_e)=(1.434\pm 0.029(stat.)\pm 0.032(syst.))\%$, which is the most precise to date. According to a detailed analysis of the involved dynamics, we find this decay is dominated with the $K^{\ast }(892{)}^{-}$ contribution and present an improved measurement of its branching fraction to be $\mathcal{B}(D^0\to K^{\ast }(892{)}^{-}{e}^{+}{\nu }_e)=(2.033\pm 0.046(stat.)\pm 0.047(syst.))\%$. We further access their hadronic form-factor ratios for the first time as $r_V=V(0)/A_1(0)=1.46\pm 0.07(stat.)\pm 0.02(syst.)$ and $r_2=A_2(0)/A_1(0)=0.67\pm 0.06(stat.)\pm 0.01(syst.)$. In addition, we observe a significant ${\bar{K}}^0{\pi }^{-}$ $S$-wave component accounting for $(5.51\pm 0.97(stat.)\pm 0.62(syst.))\%$ of the total decay rate.

8 pages, 2 figures