Measurement of the WZ cross section in the channel WZ -> lvbb at sqrt(s) = 8TeV with the ATLAS detector

In this thesis, a measurement of the total cross section of WZ production in proton-proton collisions at √s = 8 TeV is presented. The measurement is performed with the ATLAS detector in the decay channel WZ → lνbb¯ based on the 20.3 fb−1 dataset from the 2012 run of the LHC. The process WZ → lνbb¯ is one of the important backgrounds in the still-ongoing search for the H → bb¯ decay of the Standard Model Higgs boson in associated WH production. A measurement of the WZ cross section is a suitable cross-check for the WH analysis since WZ production is already a well-explored process of the Standard Model. Chapter 2 introduces the process WZ → lνbb¯ as well as the important backgrounds and gives an overview of the LHC and the ATLAS detector. Chapter 3 discusses the dataset, the simulated event samples and the object reconstruction this analysis is based on. An outline of the analysis strategy is given in chapter 4. The chapters 5 and 6 explain different analysis techniques and their application. Systematic uncertainties on the cross section measurement are discussed in chapter 7. The results are presented in chapter 8 and 9.