Measurement of the top quark mass in the fully hadronic top antitop decay channel with the ATLAS detector

A measurement of the top quark mass in the fully hadronic top-antitop decay channel is presented. The measurement uses data recorded with the ATLAS detector from proton-proton collisions provided by the LHC in 2011. The data were taken at a centre-of-mass energy of 7 TeV and correspond to an integrated luminosity of about 4.7 fb^-1.To measure the top quark mass a template technique is used, based on the so-called R_3/2 estimator which is built from the invariant mass ratio of the hadronically decaying top quarks and W bosons. A kinematic likelihood fit is performed to properly reconstruct the ttbar decay. The multijet background to the fully hadronic ttbar signal is modelled from data by means of an ABCD method, allowing for a precise prediction of kinematical distributions in background events. The top quark mass is measured to be m_top = 175.1 +- 1.4 (stat.) +- 1.8~(syst.) GeV/c^2, with the dominant sources of systematic uncertainty coming from the jet energy scale and the residual b-jet energy scale.