Observation of top quark pairs produced in association with a vector boson in pp collisions at root s=8 TeV


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Khachatryan V., Sirunyan A., Tumasyan A., Adam W., Asilar E., Bergauer T., ...More

JOURNAL OF HIGH ENERGY PHYSICS, no.1, 2016 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: Issue: 1
  • Publication Date: 2016
  • Doi Number: 10.1007/jhep01(2016)096
  • Journal Name: JOURNAL OF HIGH ENERGY PHYSICS
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Keywords: Electroweak interaction, Hadron-Hadron scattering, Top physics, R(B)
  • Çukurova University Affiliated: Yes

Abstract

Measurements of the cross sections for top quark pairs produced in association with a W or Z boson are presented, using 8 TeV pp collision data corresponding to an integrated luminosity of 19.5 fb(-1), collected by the CMS experiment at the LHC. Final states are selected in which the associated W boson decays to a charged lepton and a neutrino or the Z boson decays to two charged leptons. Signal events are identified by matching reconstructed objects in the detector to specific final state particles from t (t) over barW or t (t) over barZ decays. The t (t) over barW cross section is measured to be 382(-102)(+117) fb with a significance of 4.8 standard deviations from the background-only hypothesis. The t (t) over barZ cross section is measured to be 242(-55)(+65) fb with a significance of 6.4 standard deviations from the background-only hypothesis. These measurements are used to set bounds on five anomalous dimension-six operators that would affect the t (t) over barW and t (t) over barZ cross sections.