Precision measurement of the $D^{\ast 0}$ decay branching fractions

Abstract

Using 482 pb${}^{-1}$ of data taken at $\sqrt{s}=4.009$ GeV, we measure the branching fractions of the decays of $D^{\ast 0}$ into $D^0\ddot{I}{€}^0$ and $D^0{\hat{I}}^3$ to be $\BR(D^{*0} \to D^0π^0)=(65.5\pm 0.8\pm 0.5)%$ and $\BR(D^{*0} \to D^0γ)=(34.5\pm 0.8\pm 0.5)%$ respectively, by assuming that the $D^{\ast 0}$ decays only into these two modes. The ratio of the two branching fractions is $\BR(D^{*0} \to D^0π^0)/\BR(D^{*0} \to D^0γ) =1.90\pm 0.07\pm 0.05$, which is independent of the assumption made above. The first uncertainties are statistical and the second ones systematic. The precision is improved by a factor of three compared to the present world average values.