Search for new physics using effective field theory in 13 TeV <i>pp</i> collision events that contain a top quark pair and a boosted Z or Higgs boson
PHYSICAL REVIEW D, cilt.108, sa.3, 2023 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 108 Sayı: 3
- Basım Tarihi: 2023
- Doi Numarası: 10.1103/physrevd.108.032008
- 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
- Açık Arşiv Koleksiyonu: AVESİS Açık Erişim Koleksiyonu
- İstanbul Üniversitesi-Cerrahpaşa Adresli: Hayır
Özet
A data sample containing top quark pairs (tt over bar ) produced in association with a Lorentz-boosted Z or Higgs boson is used to search for signs of new physics using effective field theory. The data correspond to an integrated luminosity of 138 fb-1 of proton-proton collisions produced at a center-of-mass energy of 13 TeV at the LHC and collected by the CMS experiment. Selected events contain a single lepton and hadronic jets, including two identified with the decay of bottom quarks, plus an additional large-radius jet with high transverse momentum identified as a Z or Higgs boson decaying to a bottom quark pair. Machine learning techniques are employed to discriminate between tt over bar Z or tt over bar H events and events from background processes, which are dominated by tt over bar + jets production. No indications of new physics are observed. The signal strengths of boosted tt over bar Z and tt over bar H production are measured, and upper limits are placed on the tt over bar Z and tt over bar H differential cross sections as functions of the Z or Higgs boson transverse momentum. The effects of new physics are probed using a framework in which the standard model is considered to be the low-energy effective field theory of a higher energy scale theory. Eight possible dimension-six operators are added to the standard model Lagrangian, and their corresponding coefficients are constrained via fits to the data.