Search for pair-production of vector-like quarks in pp collision events at s=13 TeV with at least one leptonically decaying Z boson and a third-generation quark with the ATLAS detector

ATLAS Publications, T.M. Carter, A. Hasib, M.P. Heath, S. Palazzo, E.P. Takeva, N. Themistokleous, E.M. Villhauer, E. Zaid

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

A search for the pair-production of vector-like quarks optimized for decays into a Z boson and a third-generation Standard Model quark is presented, using the full Run 2 dataset corresponding to 139 fb−1 of pp collisions at √s = 13 TeV, collected in 2015–2018 with the ATLAS detector at the Large Hadron Collider. The targeted final state is characterized by the presence of a Z boson with
high transverse momentum, reconstructed from a pair of same-flavour leptons with opposite-sign charges, as well as by the presence of b-tagged jets and high-transverse-momentum large-radius jets reconstructed from calibrated smaller-radius jets. Events with exactly two or at least three leptons are
used, which are further categorized by the presence of boosted W , Z , and Higgs bosons and top quarks. The categorization is performed using a neural-network-based boosted object tagger to enhance the sensitivity to signal relative to the background. No significant excess above the background expectation is
observed and exclusion limits at 95% confidence level are set on the masses of the vector-like partners T and B of the top and bottom quarks, respectively. The limits depend on the branching ratio configurations and, in the case of 100% branching ratio for T → Zt and 100% branching ratio for B → Zb, this search
sets the most stringent limits to date, allowing m T > 1.60 TeV and m B > 1.42 TeV, respectively.
Original languageEnglish
Article number138019
Pages (from-to)1-25
Number of pages25
JournalPhysics Letters B
Volume843
DOIs
Publication statusPublished - 10 Aug 2023

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