Search for pair-production of vector-like quarks in lepton plus jets final states containing at least one b -tagged jet using the Run 2 data from the ATLAS experiment

• Published in: Physics letters. B Vol. 854
• Main Authors: Aad, G., Bergeås Kuutmann, Elin, Brenner, Richard, Dimitriadi, Christina, Ellajosyula, Venugopal, Ellert, Mattias, Ferrari, Arnaud, Gonzalez Suarez, Rebeca, Mathisen, Thomas, Mullier, Geoffrey A., Ripellino, Giulia, Steentoft, Jonas, Sunneborn Gudnadottir, Olga, Zwalinski, L.
• Format: Journal Article
• Language: English
• Published: 01.07.2024
• ISSN: 0370-2693; 1873-2445
• DOI: 10.1016/j.physletb.2024.138743

A search is presented for the pair-production of heavy vector-like quarks in the lepton+jets final state using 140 fb(-1) of proton-proton collisions at root s = 13 TeV collected with the ATLAS detector. The search is optimised for vector-like top-quarks (T) that decay into a W boson and a b-quark, with one W boson decaying leptonically and the other hadronically. Other vector-like quark flavours and decay modes are also considered. Events are selected with one high transverse-momentum electron or muon, large missing transverse momentum, a large-radius jet identified as a W boson, and multiple small-radius jets, at least one of which is b-tagged. Vector-like T-quarks with 100% branching ratio to Wb are excluded at 95% CL for masses below 1700 GeV. These limits are also applied to vector-like Y-quarks, which decay exclusively into a W boson and a b-quark. Isospin singlets with B(T -> Wb: Ht: Zt ) = 1/2 : 1/4 : 1/4 are excluded for masses below 1360 GeV.