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


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Jackson P., Kong A., Potti H., Ruggeri T., Sharma A., Ting E., ...Daha Fazla

PHYSICAL REVIEW D, cilt.108, sa.3, 2023 (SCI-Expanded) identifier identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 108 Sayı: 3
  • Basım Tarihi: 2023
  • Doi Numarası: 10.1103/physrevd.108.032019
  • Dergi Adı: PHYSICAL REVIEW D
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Aerospace Database, Chemical Abstracts Core, INSPEC, zbMATH
  • Ankara Üniversitesi Adresli: Evet

Özet

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 root 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 x 10(-5) (13 x 10(-5)) for t -> Zu (t -> Zc) for a left-handed tZq coupling, and 6.6 x 10(-5) (12 x 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-uW((13))*| and |C-uB((13))*| (|C-uW((31))| and |C-uB((31))|) of 0.15 (0.16), and limits for |C-uW((23))*| and |C-uB((23))*| (|C-uW((32))| and |C-uB((32))|) of 0.22 (0.21), assuming a new-physics energy scale Lambda(NP) of 1 TeV.