Measurement of the Top-Quark Mass in the Fully Hadronic Decay Channel from ATLAS Data at √s=7 TeV


The mass of the top quark is measured in a data set corresponding to 4.6 fb⁻¹ of proton-proton collisions with centre-of-mass energy √s = 7 TeV collected by the ATLAS detector at the LHC. Events consistent with hadronic decays of top-antitop quark pairs with at least six jets in the final state are selected. The substantial background from multijet production is modelled with data-driven methods that utilise the number of identified b-quark jets and the transverse momentum of the sixth leading jet, which have minimal correlation. The top-quark mass is obtained from template fits to the ratio of three-jet to dijet mass. The three-jet mass is calculated from the three jets produced in a top-quark decay. Using these three jets the dijet mass is obtained from the two jets produced in the W boson decay. The top-quark mass obtained from this fit is thus less sensitive to the uncertainty in the energy measurement of the jets. A binned likelihood fit yields a top-quark mass of m(t) = 175.1 ± 1.4 (stat.) ± 1.2 (syst.) GeV.



Partons, Standard Model, Bosons, Proton-proton interactions, Quarks, Jets (Nuclear physics), W bosons, Transverse momentum


CC BY 4.0 (Attribution), ©2015 CERN, for the ATLAS Collaboration