First Measurement of $\mathit{\Gamma }\left({\mathit{D}}^{*+}\right)$

We present the first measurement of the $D^{*+}$ width using 9/fb of $e^{+}{e}^{-}$ data collected near the $\Upsilon \left(4\mathrm{S}\right)$ resonance by the CLEO II.V detector. Our method uses advanced tracking techniques and a reconstruction method that takes advantage of the small vertical size of the Cornell Electron-positron Storage Ring beam spot to measure the energy release distribution from the $D^{*+}\to D^0{\pi }^{+}$ decay. We find $\Gamma \left(D^{*+}\right)=96\mathrm{}\pm 4\left(\mathrm{stat}\right)\pm 22\left(\mathrm{syst}\right)\mathrm{keV}$. We also measure the energy release in the decay and compute $\Delta m\equiv m_{D^{*+}}{-m}_{D^0}=145.412\mathrm{}\pm 0.002\left(\mathrm{stat}\right)\pm 0.012\left(\mathrm{syst}\right)\mathrm{MeV}/{\mathrm{c}}^2$.