Differential top-antitop cross-section measurements as a function of observables constructed from final-state particles using pp collisions at √s=7 TeV in the ATLAS detector

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Aad, G. ; Abbott, B. ; Abdallah, J. ; Abdel Khalek, S. ; Abdinov, O. ; Aben, R. ; Abi, B. ; Abolins, M. ; AbouZeid, O. S. ; Abramowicz, H. ; Abreu, H. ; Abreu, R. ; Abulaiti, Y. ; Acharya, B. S. ; Adamczyk, L. ; Adams, D. L. ; Adelman, J. ; Adomeit, S. ; Adye, T. ; Agatonovic-Jovin, T. ; Aguilar-Saavedra, J. A. ; Agustoni, M. ; Ahlen, S. P. ; Ahmadov, F. ; Aielli, G. ; Akerstedt, H. ; Åkesson, T. P. A. ; Akimoto, G. ; Akimov, A. V. ; Alberghi, G. L. ... view all 2,879 authors (2015)

Various differential cross-sections are measured in top-quark pair (tt¯) events produced in proton-proton collisions at a centre-of-mass energy of s√=7 TeV at the LHC with the ATLAS detector. These differential cross-sections are presented in a data set corresponding to an integrated luminosity of 4.6 fb−1. The differential cross-sections are presented in terms of kinematic variables, such as momentum, rapidity and invariant mass, of a top-quark proxy referred to as the pseudo-top-quark as well as the pseudo-top-quark pair system. The dependence of the measurement on theoretical models is minimal.\ud The measurements are performed on tt¯ events in the lepton+jets channel, requiring exactly one charged lepton and at least four jets with at least two of them tagged as originating from a b-quark. The hadronic and leptonic pseudo-top-quarks are defined via the leptonic or hadronic decay mode of the W boson produced by the top-quark decay in events with a single charged lepton. Differential cross-section measurements of the pseudo-top-quark variables are compared with several Monte Carlo models that implement next-to-leading order or leading-order multi-leg matrix-element calculations.
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