This paper presents a direct measurement of the decay width of the top quark using tt¯ events in the lepton+jets final state. The data sample was collected by the ATLAS detector at the LHC in proton–proton collisions at a centre-of-mass energy of 8 TeV and corresponds to an integrated luminosity of 20.2 fb- 1. The decay width of the top quark is measured using a template fit to distributions of kinematic observables associated with the hadronically and semileptonically decaying top quarks. The result, Γt=1.76±0.33(stat.)-0.68+0.79(syst.)GeV for a top-quark mass of 172.5 GeV, is consistent with the prediction of the Standard Model.

Aaboud, M., Aad, G., Abbott, B., Abdinov, O., Abeloos, B., Abidi, S.H., et al. (2018). Direct top-quark decay width measurement in the tt¯ lepton+jets channel at √s=8TeV with the ATLAS experiment. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS, 78(2) [10.1140/epjc/s10052-018-5595-5].

Direct top-quark decay width measurement in the tt¯ lepton+jets channel at √s=8TeV with the ATLAS experiment

Ceradini, F.;Di Micco, B.;Di Nardo, R.;Orestano, D.;Petrucci, F.;