Measurement of the absolute branching fraction of D <sup>+</sup> → K̅ <sup>0</sup> e <sup>+</sup> ν <sub>e</sub> via <b> K̅ <sup>0</sup> → <i>π</i> <sup>0</sup> <i>π</i> <sup>0</sup> </b>
Chinese Physics C, High Energy Physics and Nuclear Physics/Chinese physics C