Münster 2017 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 4: Top Quark 1 (Produktion)

T 4.2: Vortrag

Montag, 27. März 2017, 17:00–17:15, JUR 4

tt cross section measurement in the lepton+jets channel at 8 TeV with the ATLAS experiment — •Arwa Bannoura, Peter Maettig, and Dominic Hirschbuehl — Bergische Universität Wuppertal, Wuppertal, Germany

The measurement of the inclusive top-quark pair-production cross section in the lepton+jets channel is preformed with 20.2 fb⁻¹ of pp collision data recorded with the ATLAS detector at √s = 8 Te −0.1em V in 2012. Events are selected by requiring one lepton (electron or muon), missing transverse momentum and at least four high-p_T jets, where at least one of the jets is required to be b-tagged. Event shape based observables are fed into an artificial neural network (NN) in order to improve the separation strength between the signal and the backgrounds. The tt production cross-section is obtained from a binned maximum-likelihood fit to the neural-network discriminant and the reconstructed mass of the hadronically decaying W boson. The main background which is W+jets is estimated from a data-driven method. Also, new ideas are proposed to constrain systematic uncertainties in order to improve the precision of the measurement.