Initial measurements ofZ-boson resonance parameters ine+e−annihilation

Abstract

We have measured the mass of the Z boson to be 91.11±0.23 GeV/$c^2$, and its width to be ${1.61}_{\mathrm{-}0.43}^{+0.60\mathrm{}}$ GeV. If we constrain the visible width to its standard-model value, we find the partial width to invisible decay modes to be 0.62±0.23 GeV, corresponding to 3.8±1.4 neutrino species.