72 research outputs found

    Measurement of the View the tt production cross-section using eőľ events with b-tagged jets in pp collisions at ‚ąös = 13 TeV with the ATLAS detector

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    This paper describes a measurement of the inclusive top quark pair production cross-section (ŌÉtt¬Į) with a data sample of 3.2 fb‚ąí1 of proton‚Äďproton collisions at a centre-of-mass energy of ‚ąös = 13 TeV, collected in 2015 by the ATLAS detector at the LHC. This measurement uses events with an opposite-charge electron‚Äďmuon 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 ŌÉtt¬Į 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: ŌÉtt¬Į = 818 ¬Ī 8 (stat) ¬Ī 27 (syst) ¬Ī 19 (lumi) ¬Ī 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

    Search for strong gravity in multijet final states produced in pp collisions at ‚ąös=13 TeV using the ATLAS detector at the LHC