Abstract
Measurements of the inclusive top quark pair production cross sections in proton-proton collisions with the ATLAS detector at the Large Hadron Collider are presented. The measurements are performed requiring one or two electrons or muons in the final state. Various experimental techniques are compared. The most accurate result in obtained requiring opposite sign electrons and muons, achieves a precision of a few percent, and is in good agreement with a recent NNLO+NNLL QCD calculation. In addition, a differential measurement of the top transverse momentum and kinematic properties of the top pair system are presented. This measurement requires one electron or muon in the final state and probes our understanding of top pair production in the TeV regime and is compared to recent Monte Carlo generators and theory calculations.
Highlights
Motivations for σtt measurements : pp → tt is main production mode of the heaviest known particle σtt is an input for many analyses Experimental test of NNLO SM predictions
→ Solve equations to obtain σtt and εb → εb : reconstruction and b-tagging of jets from top decays → Correlation Cb between b-tagged jets measured on MC → Signal pre-selection efficiency εeμ measured on MC
Computation of 1/σ d σtt /dX where X = pTt, mtt, pTtt, ytt → e and μ channels combined with BLUE method
Summary
→ 1 e or μ, pT > 40 GeV and |η| < 2.5 → ≥3 jets, pT > 25 GeV and |η| < 2.5 → ≥1 b-tagged jet, MVA tagger with 70% efficiency → e+jets : EmT iss > 30 GeV and mT(W ) > 30 GeV → μ+jets : EmT iss > 20 GeV and EmT iss + mT(W ) > 60 GeV
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