Measurement of the top quark pair production charge asymmetry in proton-proton collisions at 7 TeV using the ATLAS detector

G. Aad, B. Abbott, J. Abdallah, S. Abdel-Khalek, O. Abdinov, R. Aben, B. Abi, Mogens Dam, Jørn Dines Hansen, Jørgen Beck Hansen, Stefania Xella, Peter Henrik Hansen, Troels Christian Petersen, Lotte Ansgaard Thomsen, Sascha Mehlhase, Morten Dam Jørgensen, Almut Maria Pingel, Ask Emil Løvschall-Jensen, Alejandro Alonso Diaz, James William MonkLars Egholm Pedersen, Graig Wiglesworth, Gorm Aske Gram Krohn Galster

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Abstract

This paper presents a measurement of the top quark pair (tt̄) production charge asymmetry AC using 4.7 fb-1 of proton-proton collisions at a centre-of-mass energy √s = 7TeV collected by the ATLAS detector at the LHC. A tt̄-enriched sample of events with a single lepton (electron or muon), missing transverse momentum and at least four high transverse momentum jets, of which at least one is tagged as coming from a b-quark, is selected. A likelihood fit is used to reconstruct the tt̄ event kinematics. A Bayesian unfolding procedure is employed to estimate AC at the parton-level. The measured value of the tt̄ production charge asymmetry is AC = 0.006 ± 0.010, where the uncertainty includes both the statistical and the systematic components. Differential AC measurements as a function of the invariant mass, the rapidity and the transverse momentum of the tt̄- system are also presented. In addition, AC is measured for a subset of events with large tt̄ velocity, where physics beyond the Standard Model could contribute. All measurements are consistent with the Standard Model predictions.

OriginalsprogEngelsk
Artikelnummer107
TidsskriftJournal of High Energy Physics (Online)
Vol/bind2014
Udgave nummer177
ISSN1126-6708
DOI
StatusUdgivet - 25 feb. 2014

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