First Measurement of Γ(D*+)

Abstract

We present the first measurement of the ${D}^{*+}$ width using 9/fb of ${e}^{+}{e}^{\ensuremath{-}}$ data collected near the $\ensuremath{\Upsilon}(4\mathrm{S})$ 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 ${D}^{*+}\ensuremath{\rightarrow}{D}^{0}{\ensuremath{\pi}}^{+}$ decay. We find $\ensuremath{\Gamma}({D}^{*+})\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}96\ifmmode\pm\else\textpm\fi{}4(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}22(\mathrm{syst})\mathrm{keV}$. We also measure the energy release in the decay and compute $\ensuremath{\Delta}m\ensuremath{\equiv}{m}_{{D}^{*+}}{\ensuremath{-}m}_{{D}^{0}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}145.412\ifmmode\pm\else\textpm\fi{}0.002(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.012(\mathrm{syst})\mathrm{MeV}/{\mathrm{c}}^{2}$.