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Title: 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

The W boson helicity fractions from top quark decays in $$t\bar{t}$$ events are measured using data from proton–proton collisions at a centre-of-mass energy of 8TeV . 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) , F L = 0.323 ± 0.008(stat) ± 0.014(syst), and F R = -0.004 ± 0.005(stat) ± 0.014(syst) for the longitudinal, left-, and right-handed components of the helicity, respectively. Furthermore, these measurements of the W boson helicity fractions are the most accurate to date and they agree with the predictions from the standard model.
  1. Yerevan Physics Inst. (YerPhI) (Armenia). et al.
Publication Date:
OSTI Identifier:
Report Number(s):
FERMILAB-PUB-16-192-CMS; CMS-TOP-13-008; CERN-EP-2016-118; arXiv:1605.09047
Journal ID: ISSN 0370-2693; 1466294
Grant/Contract Number:
Published Article
Journal Name:
Physics Letters. Section B
Additional Journal Information:
Journal Volume: 762; Journal Issue: C; Journal ID: ISSN 0370-2693
Research Org:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Contributing Orgs:
CMS Collaboration
Country of Publication:
United States
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; CMS; physics; top; anomalous couplings; helicity