Electron identification and ZZ -->4l̳ (e̳, [mu]) cross section measurement with the CMS detector

Abstract

We perform multiple analyses using generator-level information in the Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC). In particular, we carry out three central investigations: the determination of electron efficiencies, electron fake rates, and ZZ -->4l(e, [mu]) cross sections. Reconstructed Z boson decays are used as a benchmark in association with our cut-based analysis. In the Z-->2e channel we find an overall electron efficiency of 77.0%± 1.3%, and electron fake rates are calculated to be (1.7 ± 0.5) . 10-3 and (0.6 ± 0.2) 10-3 for the photon jet and QCD channels, respectively. We calculate an expected total of 17 counts/fb-1 for ZZ-->4l, which we find to have a cross section of [sigma]zz-->4l = 180 ± 45 ± 6 fb (with statistical uncertainty listed before systematic uncertainty). From our analysis using generatorlevel information, we obtain a set of reconstruction-level techniques that will be useful once the LHC starts delivering pp collisions sometime in 2008.