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Measurement of the tt¯ production cross-section using eμ events with b -tagged jets in pp collisions at √s = 13 TeV with the ATLAS detector

CollaborationWith : Ancu, Lucian Stefan / Bilbao De Mendizabal, Javier / Calace, Noemi / Chatterjee, Avishek / Clark, Allan Geoffrey / Coccaro, Andrea / Delitzsch, Chris Malena / Della Volpe, Domenico / Ferrere, Didier / Gadomski, Szymon / Golling, Tobias / Gonzalez Sevilla, Sergio / Gramling, Johanna Léna / Guescini, Francesco / Iacobucci, Giuseppe / Katre, Akshay / Khoo, Teng Jian / Lionti, Anthony Eric / March Ruiz, Luis / Mermod, Philippe / Miucci, Antonio / Nackenhorst, Olaf / Paolozzi, Lorenzo / Ristic, Branislav / Schramm, Steven / Sfyrla, Anna / Vallecorsa, Sofia / Wu, Xin
Published in Physics Letters. B. 2016
Collection SCOAP3
Abstract This paper describes a measurement of the inclusive top quark pair production cross-section ( σtt¯ ) with a data sample of 3.2fb−1 of proton–proton collisions at a centre-of-mass energy of s=13TeV , collected in 2015 by the ATLAS detector at the LHC. This measurement uses events with an opposite-charge electron–muon pair in the final state. Jets containing b -quarks are tagged using an algorithm based on track impact parameters and reconstructed secondary vertices. The numbers of events with exactly one and exactly two b -tagged jets are counted and used to determine simultaneously σtt¯ and the efficiency to reconstruct and b -tag a jet from a top quark decay, thereby minimising the associated systematic uncertainties. The cross-section is measured to be: σtt¯=818±8(stat)±27(syst)±19(lumi)±12(beam) pb, where the four uncertainties arise from data statistics, experimental and theoretical systematic effects, the integrated luminosity and the LHC beam energy, giving a total relative uncertainty of 4.4%. The result is consistent with theoretical QCD calculations at next-to-next-to-leading order. A fiducial measurement corresponding to the experimental acceptance of the leptons is also presented.
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ATLAS COLLABORATION. Measurement of the tt¯ production cross-section using eμ events with b -tagged jets in pp collisions at √s = 13 TeV with the ATLAS detector. In: Physics Letters. B, 2016. https://archive-ouverte.unige.ch/unige:86548

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Deposited on : 2016-09-02

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