Measurement of the t¯tZ and t¯tW cross sections in proton-proton collisions at √s=13 TeV with the ATLAS detector
Aaboud, Morad; Aad, Georges; Abbott, Brad; Abbott, Dale C.; Abdinov, Ovsat Bahram oglu; Abeloos, Baptiste; Abhayasinghe, Deshan Kavishka; Abidi, Syed Haider; AbouZeid, Hass; Abraham, Nadine L.; Buanes, Trygve; Djuvsland, Julia Isabell; Eigen, Gerald; Fomin, Nikolai; Lipniacka, Anna; Martin dit Latour, Bertrand; Mæland, Steffen; Stugu, Bjarne; Yang, Zongchang; Bugge, Magnar Kopangen; Cameron, David Gordon; Catmore, James Richard; Feigl, Simon; Garonne, Vincent; Gramstad, Eirik; Hellesund, Simen; Morisbak, Vanja; Oppen, Henrik; Ould-Saada, Farid; Pedersen, Maiken; Read, Alexander Lincoln; Røhne, Ole Myren; Sandaker, Heidi; Serfon, Cédric; Vadla, Knut Oddvar Høie; Abramowicz, Halina; Abreu, Henso; Abulaiti, Yiming; Acharya, Bobby S.; Adachi, Shunsuke; Adam, Lennart; Adamczyk, Leszek; Adamek, Lukas; Adelman, Jareed; Adersberger, Michael; Adigüzel, Aytül; Adye, Tim; Affolder, Anthony Allen; Afik, Yoav; Agheorghiesei, Catalin; ATLAS, Collaboration
Peer reviewed, Journal article
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A measurement of the associated production of a top-quark pair ( t ¯ t ) with a vector boson ( W , Z ) in proton-proton collisions at a center-of-mass energy of 13 TeV is presented, using 36.1 fb − 1 of integrated luminosity collected by the ATLAS detector at the Large Hadron Collider. Events are selected in channels with two same- or opposite-sign leptons (electrons or muons), three leptons or four leptons, and each channel is further divided into multiple regions to maximize the sensitivity of the measurement. The t ¯ t Z and t ¯ t W production cross sections are simultaneously measured using a combined fit to all regions. The best-fit values of the production cross sections are σ t ¯ t Z = 0.95 ± 0.0 8 stat ± 0.1 0 syst pb and σ t ¯ t W = 0.87 ± 0.1 3 stat ± 0.1 4 syst pb in agreement with the Standard Model predictions. The measurement of the t ¯ t Z cross section is used to set constraints on effective field theory operators which modify the t ¯ t Z vertex.