Improved $W$ boson mass measurement with the DØ detector

We have measured the W boson mass using the DØ detector and a data sample of $82\hspace{0.5em}{\mathrm{pb}}^{-1}$ from the Fermilab Tevatron collider. This measurement uses $\overrightarrow{W}e\nu$ decays, where the electron is close to a boundary of a central electromagnetic calorimeter module. Such “edge” electrons have not been used in any previous DØ analysis, and represent a 14% increase in the W boson sample size. For these electrons, new response and resolution parameters are determined, and revised backgrounds and underlying event energy flow measurements are made. When the current measurement is combined with previous DØ W boson mass measurements, we obtain $M_W=80.483\mathrm{}\pm 0.084\hspace{0.5em}\mathrm{GeV}.$ The 8% improvement from the previous DØ measurement is primarily due to the improved determination of the response parameters for non-edge electrons using the sample of Z bosons with non-edge and edge electrons.