Khachatryan, V.Sirunyan, A. M.Tumasyan, A.Adam, W.Asilar, E.Bergauer, T.The CMS Collaboration2025-03-072025-03-0720160370-26931873-2445https://doi.org/10.1016/j.physletb.2016.10.007https://hdl.handle.net/20.500.12507/3031The W boson helicity fractions from top quark decays in t (t) over bar 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 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. (C) 2016 The Author. Published by Elsevier B.V.eninfo:eu-repo/semantics/openAccessCMSPhysicsTopAnomalous couplingsHelicityArticle762512534WOS:0003884737000712-s2.0-8499403019710.1016/j.physletb.2016.10.007Q1Q1