Title: Measurement of Charm Meson Lifetimes

Abstract: We report measurements of the $D^0, D^+$, and $D^+_s$ meson lifetimes using $3.7 fb^{-1}$ of e^+e^- annihilation data collected near the $\Upsilon(4S)$ resonance with the CLEO detector. The lifetimes of the $D^0, D^+$, and $D^+_s$ mesons are measured to be $408.5 \pm 4.1 ^{+3.5}_{-3.4} fs, 1033.6 \pm 22.1 ^{+9.9}_{-12.7} fs$, and $486.3 \pm 15.0 ^{+4.9}_{-5.1} fs$, respectively. The precisions of the charm meson lifetimes reported here are comparable to those of the best previous measurements, and the systematic errors are very different. In a single experiment we find that the ratio of the $D^+_s$ and $D^0$ lifetimes differs from one by more than 4.5 standard deviations.