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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√= 8TeV
Journal article   Open access   Peer reviewed

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√= 8TeV

Vardan Khachatryan, Felix Bachmair, Lukas Bäni, Lorenzo Bianchini, Bruno Casal, Günther Dissertori, Michael Dittmar, Mauro Donegà, Philipp Eller, Christoph Grab, …
Physics letters. B, Vol.762, pp.512-534
11/10/2016
DOI: 10.1016/j.physletb.2016.10.007
url
https://doi.org/10.1016/j.physletb.2016.10.007View
Published (Version of record) Open Access

Abstract

The 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.
High Energy Physics Experiment Nuclear Experiment

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