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Measurement of the ttZ production cross section in the three lepton final state with 13.0 fb−¹ of √s = 8 TeV pp collision data collected by the ATLAS detector

University of British Columbia

A measurement of the ttZ production cross section with the ATLAS detector in pp collisions at the LHC is presented. The search is performed on 13.0 fb−¹ of data collected in 2012. Only final states with three leptons are considered, in which the Z boson decays to a pair of leptons and one of the W bosons coming from t → bW decays gives rise to a lepton after decay. An excess of 8.95 ± 0.62 (stat) +0.37 -0.59(sys) events above background is observed with a significance of 3.64 standard deviations above zero. We have assumed no statistical error on the acceptance or efficiency of detection. In the trilepton channel, a direct measurement of the ttZ production cross section of σ = 254 ± 104 (stat) ± 19 (sys) fb is obtained.

Text

2013-03-22

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/44055

Physics

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/