Measurement of theD+andD0lifetimes

We have used a silicon-microstrip vertex detector with Tagged Photon spectrometer to measure the lifetimes of charmed mesons produced by a high-energy photon beam at Fermilab. The $D^{+}$ lifetime, based on 969 $D^{+}$→$K^{\mathrm{-}}$ ${\pi }^{+}$ ${\pi }^{+}$ decays, is measured to be (1.06±0.05±0.03)×${10}^{\mathrm{-}12}$ s. Using 1360 $D^0$ decays into the modes $K^{\mathrm{-}}$ ${\pi }^{+}$ and $K^{\mathrm{-}}$ ${\pi }^{+}$ ${\pi }^{\mathrm{-}}$ ${\pi }^{+}$, we determine the lifetime to be (0.435±0.015±0.010)×${10}^{-12}$ s. The ratio τ($D^{+}$)/τ($D^0$) obtained from these two measurements is 2.44±0.14±0.08.