Measurement of the branching ratios $\Gamma (D_s^{*+}\to D_s^{+}{\pi }^0)/\Gamma (D_s^{*+}\to D_s^{+}\gamma )$ and $\Gamma (D^{*0}\to D^0{\pi }^0)/\Gamma (D^{*0}\to D^0\gamma )$

Data samples corresponding to the isospin-violating decay $D_s^{*+}\to D_s^{+}{\pi }^0$ and the decays $D_s^{*+}\to D_s^{+}\gamma$, $D^{*0}\to D^0{\pi }^0$ and $D^{*0}\to D^0\gamma$ are reconstructed using $90.4$ ${\mathrm{fb}}^{-1}$ of data recorded by the BABAR detector at the PEP-II asymmetric-energy $e^{+}{e}^{-}$ collider. The following branching ratios are extracted: $\Gamma (D_s^{*+}\to D_s^{+}{\pi }^0)/\Gamma (D_s^{*+}\to D_s^{+}\gamma )=0.062\pm 0.005(\mathrm{stat}.)\pm 0.006(\mathrm{syst}.)$ and $\Gamma (D^{*0}\to D^0{\pi }^0)/\Gamma (D^{*0}\to D^0\gamma )=1.74\pm 0.02(\mathrm{stat}.)\pm 0.13(\mathrm{syst}.)$. Both measurements represent significant improvements over present world averages.

Figure 1

The $K^{+}{K}^{-}{\pi }^{+}$ mass distribution. The dots represent data points with error bars corresponding to statistical uncertainties (these uncertainties are small enough that the error bars are difficult to distinguish). The solid curve shows the fitted function. The dashed curve indicates the background. $D_s^{+}$ candidates are defined by the region between the vertical dotted lines.

Figure 2

The $D_s^{*+}$ signals: (a) $m(K^{+}{K}^{-}{\pi }^{+}{\pi }^0)-m(K^{+}{K}^{-}{\pi }^{+})$; (b) $m(K^{+}{K}^{-}{\pi }^{+}\gamma )-m(K^{+}{K}^{-}{\pi }^{+})$. The dots represent data points. The solid curve shows the fitted function. The dashed curve indicates the portion of the fit associated with background.

Figure 3

The measured values of (a) $\Gamma (D_s^{*+}\to D_s^{+}{\pi }^0)/\Gamma (D_s^{*+}\to D_s^{+}\gamma )$ and (b) $\Gamma (D^{*0}\to D^0{\pi }^0)/\Gamma (D^{*0}\to D^0\gamma )$ in intervals of center-of-mass momentum $p^{*}$. The error bars indicate the associated statistical error. The solid line (dashed line) is the result of a fit to a constant (first-order polynomial). The dotted line is the result from the entire sample integrated over $p^{*}$.

Figure 4

The $D^{*0}$ signals: (a) $m(K^{-}{\pi }^{+}{\pi }^0)-m(K^{-}{\pi }^{+})$ and (b) $m(K^{-}{\pi }^{+}\gamma )-m(K^{-}{\pi }^{+})$. The dots represent data points. The solid curve shows the fitted function. The dashed curve indicates the portion of the fit associated with background.