Search for new physics using effective field theory in 13 TeV pp collision events that contain a top quark pair and a boosted Z or Higgs boson
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Type :
Article
Publication Status :
Published
Access :
Attribution 4.0 International
openAccess
https://creativecommons.org/licenses/by/4.0/
openAccess
https://creativecommons.org/licenses/by/4.0/
Abstract
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.
Source :
Physical Review D
Date :
2023-08-10
Volume :
108
Issue :
3
Publisher :
American Physical Society
URI
http://hdl.handle.net/10679/8984https://journals.aps.org/prd/abstract/10.1103/PhysRevD.108.032008
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