The $D^{\circ }$ Cabibbo-suppressed decay modes ${\pi }^{-}{\pi }^{+}$ and $K^{-}{K}^{+}$ have been observed and the following ratios of $D^{\circ }$ partial decay widths have been measured: $\frac{\Gamma (D^{\circ }\to {\pi }^{-}{\pi }^{+})}{\Gamma (D^{\circ }\to K^{-}{\pi }^{+})}=0.033\mathrm{}\pm 0.015$ and $\frac{\Gamma (D^{\circ }\to K^{-}{K}^{+})}{\Gamma (D^{\circ }\to K^{-}{\pi }^{+})}=0.113\mathrm{}\pm 0.030$.

• Received 11 June 1979

DOI:https://doi.org/10.1103/PhysRevLett.43.481