Search for flavor-changing neutral-current couplings between the top quark and the Z boson with proton-proton collisions at s=13 TeV with the ATLAS detector

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

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

A search for flavor-changing neutral-current couplings between a top quark, an up or charm quark, and a Z boson is presented, using proton–proton collision data at √s=13  TeV collected by the ATLAS detector at the Large Hadron Collider. The analyzed data set corresponds to an integrated luminosity of 139  fb−1. The search targets both single-top-quark events produced as gq→tZ (with q=u, c) and top-quark-pair events, with one top quark decaying through the t→Zq channel. The analysis considers events with three leptons (electrons or muons), a b-tagged jet, possible additional jets, and missing transverse momentum. The data are found to be consistent with the background-only hypothesis and 95% confidence-level limits on the t→Zq branching ratios, assuming only tensor operators of the Standard Model effective field theory framework contribute to the tZq vertices. These are 6.2×10−5 (13×10−5) for t→Zu (t→Zc) for a left-handed tZq coupling, and 6.6×10−5 (12×10−5) in the case of a right-handed coupling. These results are interpreted as 95% CL upper limits on the strength of the corresponding couplings, yielding limits for |C(13)*uW| and |C(13)*uB| (|C(31)uW| and |C(31)uB|) of 0.15 (0.16), and limits for |C(23)*uW| and |C(23)*uB| (|C(32)uW| and |C(32)uB|) of 0.22 (0.21), assuming a new-physics energy scale ΛNP of 1 TeV.
Original languageEnglish
Article number032019
Pages (from-to)1-34
Number of pages34
JournalPhysical Review D
Volume108
Issue number3
DOIs
Publication statusPublished - 30 Aug 2023

Keywords / Materials (for Non-textual outputs)

  • Plus Plus
  • Parton Distributions
  • Pair Production
  • Physics
  • Decay

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