Improved measurement of absolute branching fraction of the inclusive decay

By analyzing 4.5 fb of $\textit{e}$ $\textit{e}$ collision data accumulated with the BESIII detector at center-of-mass energies ranging from 4599.53 MeV to 4698.82 MeV, we report the measurement of the absolute branching fraction (BF) of the inclusive decay using the double-tag technique. The result is = (10.9 $\textit{±}$ 0.2 $\textit{±}$ 0.1)%, where the first uncertainty is statistical and the second is systematic. This result indicates that there are still undiscovered decay channels containing in the final state with a combined BF of (3.0 $\textit{±}$ 0.4)%. The BF of the inclusive decay is calculated to be = (21.8 $\textit{±}$ 0.4 $\textit{±}$ 0.2)%, The result is in agreement with the prediction of the statistical isospin model.