Measurement of theWBoson Mass Using Electrons at Large Rapidities

We report a measurement of the $W$ boson mass based on an integrated luminosity of $82{\mathrm{pb}}^{-1\mathrm{}}$ from $p\overline{p}$ collisions at $\sqrt{s}=1.8\mathrm{}\mathrm{TeV}$ recorded in 1994–1995 by the D0 detector at the Fermilab Tevatron. We identify $W$ bosons by their decays to $e\nu$, where the electron is detected in the forward calorimeters. We extract the mass by fitting the transverse mass and the electron and neutrino transverse momentum spectra of 11 089 $W$ boson candidates. We measure $M_W=80.691\mathrm{}\pm 0.227\mathrm{GeV}$. By combining this measurement with our previously published central calorimeter results from data taken in 1992–1993 and 1994–1995, we obtain $M_W=80.482\mathrm{}\pm 0.091\mathrm{GeV}$.