The measurement of MW from the W+W− threshold cross section at LEP2 Original Research Article

The rapid increase of the e+e− → W+W− cross section in the threshold region provides a method for measuring Mw at LEP2. The dependence of the theoretical cross section - including the effects of the finite W width, Coulomb interactions and initial state radiation - on the collider energy and on the mass and width of the W is investigated in order to deduce the optimal collider energy which maximizes the sensitivity to Mw. Statistical and systematic uncertainties are studied in detail. The background contribution from QCD four-jet production is estimated. It is shown that by running LEP2 at ∝ ∼ 161 GeV and obtaining a luminosity of order 100 pb-ʹ per experiment, an uncertainty on the measured value of Mw of ±70 MeV should be achievable.