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
Physics Letters B
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 8TeV. The data were collected in 2012 with the CMS detector at the LHC, corresponding to an integrated luminosity of 19.8fb−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.
Baarmand, M M.; Bhopatkar, Vallary; Colafranceschi, Stefano; Hohlmann, Marcus; Noonan, D; Roy, Tuhin S.; Yumiceva, Francisco X.; and CMS Collaboration, "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" (2016). Aerospace, Physics, and Space Science Faculty Publications. 110.