Search for heavy particles decaying into top-quark pairs using lepton-plus-jets events in proton-proton collisions at s = 13 TeV with the ATLAS detector.

A search for new heavy particles that decay into top-quark pairs is performed using data collected from proton-proton collisions at a centre-of-mass energy of 13 TeV by the ATLAS detector at the Large Hadron Collider. The integrated luminosity of the data sample is 36.1fb - 1 . Events consistent with top-quark pair production are selected by requiring a single isolated charged lepton, missing transverse momentum and jet activity compatible with a hadronic top-quark decay. Jets identified as likely to contain b-hadrons are required to reduce the background from other Standard Model processes. The invariant mass spectrum of the candidate top-quark pairs is examined for local excesses above the background expectation. No significant deviations from the Standard Model predictions are found. Exclusion limits are set on the production cross-section times branching ratio for hypothetical Z ' bosons, Kaluza-Kein gluons and Kaluza-Klein gravitons that decay into top-quark pairs.

Aaboud, M., Aad, G., Abbott, B., Abdinov, O., Abeloos, B., Abidi, S. H., ... ATLAS Collaboration.

Aaboud, M||Aad, G||Abbott, B||Abdinov, O||Abeloos, B||Abidi, SH||AbouZeid, OS||Abraham, NL||Abramowicz, H||Abreu, H||Abulaiti, Y||Acharya, BS||Adachi, S||Adamczyk, L||Adelman, J||Adersberger, M||Adiguzel, A||Adye, T||Affolder, AA||Afik, Y||Agheorghiesei, C||Aguilar-Saavedra, JA||Ahmadov, F||Aielli, G||Akatsuka, S||Åkesson, TPA||Akilli, E||Akimov, AV||Alberghi, GL||Albert, J||Albicocco, P||Alconada Verzini, MJ||Alderweireldt, S||Aleksa, M||Aleksandrov, IN||Alexa, C||Alexander, G||Alexopoulos, T||Alhroob, M||Ali, B||Aliev, M||Alimonti, G||Alison, J||Alkire, SP||Allaire, C||Allbrooke, BMM||Allen, BW||Allport, PP||Aloisio, A||Alonso, A||Alonso, F||Alpigiani, C||Alshehri, AA||Alstaty, MI||Alvarez Gonzalez, B||Álvarez Piqueras, D||Alviggi, MG||Amadio, BT||Amaral Coutinho, Y||Ambroz, L||Amelung, C||Amidei, D||Amor Dos Santos, SP||Amoroso, S||Amrouche, CS||Anastopoulos, C||Ancu, LS||Andari, N||Andeen, T||Anders, CF||Anders, JK||Anderson, KJ||Andreazza, A||Andrei, V||Angelidakis, S||Angelozzi, I||Angerami, A||Anisen

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