Measurement of the W boson helicity fractions in the decays of top quark pairs to lepton+jets final states produced in pp collisions at √s = 8 TeV

CMS Collaboration

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Abstract

The W boson helicity fractions from top quark decays in tt‾ events are measured using data from proton–proton collisions at a centre-of-mass energy of 8 TeV. The data were collected in 2012 with the CMS detector at the LHC, corresponding to an integrated luminosity of 19.8 fb−1. Events are reconstructed with either one muon or one electron, along with four jets in the final state, with two of the jets being identified as originating from b quarks. The measured helicity fractions from both channels are combined, yielding F0 = 0.681 ±0.012 (stat)±0.023 (syst), FL= 0.323 ±0.008 (stat)±0.014 (syst), and FR=−0.004 ±0.005 (stat)±0.014 (syst) for the longitudinal, left-, and right-handed components of the helicity, respectively. These measurements of the W boson helicity fractions are the most accurate to date and they agree with the predictions from the standard model.
Original languageEnglish
Pages (from-to)512-534
Number of pages23
JournalPhysics Letters B
Volume762
DOIs
Publication statusPublished - 2016
Externally publishedYes

Keywords

  • CMS
  • Physics
  • Top
  • Anomalous couplings
  • Helicity

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