Top-quark mass measurement in the all-hadronic top-antitop quark decay channel at sqrt(s) = 8 TeV with the ATLAS detector

The top-quark mass is measured in the all-hadronic top-antitop quark decay channel using proton--proton collisions at a centre-of-mass energy of sqrt(s )= 8 TeV with the ATLAS detector at the CERN Large Hadron Collider. The data set used in the analysis corresponds to an integrated luminosity of 20.2 fb-1. The analysis is performed on events containing at least six jets, at least two of which must be originating from b-quarks. The reconstruction of the top quark pair and the W bosons in each event is performed using a chi^2 method. The large QCD multi-jet background is modelled using a data-driven method. The top-quark mass is obtained from template fits to the ratio of the three-jet to the dijet mass. The three-jet mass is obtained from the three jets assigned to the top quark decay. From these three jets the dijet mass is obtained using the two jets assigned to the W boson decay. The top-quark mass is measured to be 173.80 +/- 0.55 (stat.) +/- 1.01 (syst.) GeV.