Analysis of W and Z Production at $\sqrt{s}$ = 7 TeV with the CMS Detector

The production of W and Z bosons is a benchmark at the startup of a high-energy hadron collider. With their sizable cross sections and clean signatures they can be utilized to test the Standard Model at an early stage of data-taking and also test the performance of the detector and the simulation. In this thesis the inclusive production of W and Z bosons in the muon channel is studied with 36 pb−1 of data collected with the CMS detector in 2010 in proton-proton collisions at a center- of-mass energy of √s = 7 TeV. In order to measure the production cross sections and their ratios, data-driven analysis techniques are applied for the determination of single-muon effi- ciencies, the estimation of backgrounds and an evaluation of the hadronic energy in W and Z events. The inclusive cross section for W production in the muon channel is measured to be 9.97 ± 0.03 (stat) ± 0.28 (syst) ± 0.40 (lumi) nb and the ratio of the inclusive cross sections for W + and W − is determined to 1.44 ± 0.01 (stat) ± 0.03 (syst). The inclusive cross section for Z/γ∗ production in the muon channel in the invariant mass range 60 GeV < Mµµ < 120 GeV is determined to 0.955 ± 0.009 (stat) ± 0.023 (syst) ± 0.038 (lumi) nb, leading to a ratio of the W and Z/γ∗ cross sections of 10.44 ± 0.10 (stat) ± 0.30 (syst). The results are in agreement with the theoretical predictions of the Standard Model. The W boson mass is an important parameter for tests of the consistency of the Standard Model. It is determined to 80.43 ± 0.05 (stat) ± 0.13 (syst) GeV in agreement with the more precise mea- surements that dominate the world average.