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

Abstract : The W boson helicity fractions from top quark decays in t-tbar 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 inverse-femtobarns. 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 F[0] = 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. These measurements of the W boson helicity fractions are the most accurate to date and they agree with the predictions from the standard model.
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Journal articles
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http://hal.in2p3.fr/in2p3-01323689
Contributor : Sylvie Flores <>
Submitted on : Tuesday, May 31, 2016 - 7:04:40 AM
Last modification on : Wednesday, July 17, 2019 - 9:06:16 AM

### Citation

V. Khachatryan, M. Besançon, F. Couderc, M. Dejardin, D. Denegri, et al.. Measurement of the W boson helicity fractions in the decays of top quark pairs to lepton+jets final states produced in pp collisions at sqrt(s) = 8 TeV. Physics Letters B, Elsevier, 2016, 762, pp.512-534. ⟨10.1016/j.physletb.2016.10.007⟩. ⟨in2p3-01323689⟩

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