Measurement of the top quark pair production charge asymmetry in proton-proton collisions at √s = 7 TeV using the ATLAS detector
Buanes, Trygve; Burgess, Thomas; Eigen, Gerald; Kastanas, Alex; Liebig, Wolfgang; Lipniacka, Anna; Rosendahl, Peter Lundgaard; Sandaker, Heidi; Sjursen, Therese B.; Stugu, Bjarne; Tonoyan, Arshak; Ugland, Maren; Bugge, Lars; Cameron, David Gordon; Czyczula, Zofia; Gjelsten, Børge Kile; Gramstad, Eirik; Lund, Esben; Ould-Saada, Farid; Pajchel, Katarina; Pedersen, Maiken; Pylypchenko, Yuriy; Read, Alexander Lincoln; Røhne, Ole Myren; Smestad, Lillian; Stapnes, Steinar; Strandlie, Are; Aad, Georges; Abajyan, Tatevik; Abbott, Brad; Abdallah, Jalal; Abdel Khalek, Samah; Abdinov, Ovsat Bahram oglu; Aben, Rosemarie; Abi, Babak; Abolins, Maris; AbouZeid, Hass; Abreu, Henso; Adamczyk, Leszek; Adams, David; Addy, Tetteh N.; Adelman, Jareed; Adomeit, Stefanie; Adye, Tim; Agatonovic-Jovin, Tatjana; Aguilar Saavedra, Juan Antonio; Agustoni, Marco; Ahles, Florian; Ahmad, Aharrouche; Aielli, Giulio; ATLAS, Collaboration
Peer reviewed, Journal article
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This paper presents a measurement of the top quark pair ( tt¯ ) production charge asymmetry A C using 4.7 fb−1 of proton-proton collisions at a centre-of-mass energy s√ = 7 TeV collected by the ATLAS detector at the LHC. A tt¯ -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 tt¯ event kinematics. A Bayesian unfolding procedure is employed to estimate A C at the parton-level. The measured value of the tt¯ production charge asymmetry is A C = 0.006 ± 0.010, where the uncertainty includes both the statistical and the systematic components. Differential A C measurements as a function of the invariant mass, the rapidity and the transverse momentum of the tt¯ system are also presented. In addition, A C is measured for a subset of events with large tt¯ velocity, where physics beyond the Standard Model could contribute. All measurements are consistent with the Standard Model predictions.