Göttingen 2012 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 32: Top-Quark: Produktion 1

T 32.5: Gruppenbericht

Montag, 27. Februar 2012, 17:45–18:05, ZHG 104

tt production cross section measurement in the dilepton channel at ATLAS — •Kirika Uchida, Tatevik Abajyan, Markus Cristinziani, Sara Ghasemi, Gia Khoriauli, Agnieszka Leyko, Ralph Schaefer, and Kaven Yau — Universitaet Bonn

The tt production cross section has been measured in the dilepton channel with 0.70fb⁻¹ data in the ATLAS experiment. The precision is down to 10% in the dilepton channel measurement only. Cut and count analyses were performed in multiple ways and the results are combined. Drell-Yan (except for τ decays) and fake leptons are estimated in data-driven methods and the uncertainty on the cross section measurements from those backgrounds are below 2%. Two analyses are characterized by the selections where both require two isolated leptons and the b-tagging is applied for one of the analysis. Cut optimizations are performed separately and systematic uncertainty sources contribute differently in the cross section measurements. However, the performance of the two measurements are similar that results in a total systematic uncertainty of ∼10% and statistical uncertainty of ∼3%. The measured cross sections are consistent with each other and also with the theoretical expectation.