Measurements of the properties ofD-meson decays

We present a study of the decay properties of charmed $D$ mesons produced near the peak of the ${\psi }^{\prime \prime }\mathrm{}\left(3770\right)\mathrm{}$ resonance in $e^{+}{e}^{-}$ annihilation. Branching fractions for nine Cabibbo-favored and three Cabibbo-suppressed decay modes are presented along with upper limits on one additional Cabibbo-favored and four additional Cabibbo-suppressed decay modes. A study of $K\pi \pi$-decay-mode Dalitz plots reveals a large quasi-two-body pseudoscalar-vector component for the $D^0$ decays and an apparent nonuniform population on the Dalitz plot for the $D^{+}$ decay into $K^{-}{\pi }^{+}{\pi }^{+}$. Using tagged events, we measure the charged-particle multiplicity and strange-particle content of $D$ decays. A measurement of the $D^{+}$ and $D^0$ semileptonic decay fractions indicates that the $D^{+}$ has a significantly longer lifetime than the $D^0$.