Determination of the Absolute Lepton Scale Using Z Boson Decays: Application to the Measurement of MW

This note describes a method to extract the EM calorimeter parameters from Z boson decays into electrons. Assuming an integrated luminosity of 10 fb-1, the absolute detector scale can be determined with a relative precision of 2.10-5, and the expected precision on the average detector resolution is 2.10-3. Exploiting the electrons energy distribution, the detector linearity can be controlled with a precision of 1.7 10-4 for electron energies between 20 and 140 GeV. The energy dependence of the resolution is measured accurately, providing 2% precision on the sampling term, and 5% precision on the calorimeter global constant term. With this knowledge, the related uncertainty on the W boson mass measurement is smaller than 4 MeV, using the EM calorimeter only.}