A measurement is presented of the top-quark mass in the all-jets channel using a sample of ttbar candidate events requiring at least six jets in the final state. The data have been collected by CMS in pp collisions at 7 TeV and correspond to an integrated luminosity of 3.54/fb. In this channel, a very tight event selection is needed to reduce the huge amount of multi-jet events. In addition, the signal fraction and mass resolution is improved by the use of a kinematic fit. An ideogram method is

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... used to measure the top-quark mass with the background estimated from data through an event mixing technique. The top-quark mass is measured to be m t = 173.5 ± 0.7(stat.) ± 1.3(syst.) GeV. Abstract. A measurement is presented of the top-quark mass in the all-jets channel using a sample of tt candidate events requiring at least six jets in the final state. The data have been collected by CMS in pp collisions at 7 TeV and correspond to an integrated luminosity of 3.54 fb −1 . In this channel, a very tight event selection is needed to reduce the huge amount of multi-jet events. In addition, the signal fraction and mass resolution is improved by the use of a kinematic fit. An ideogram method is used to measure the top-quark mass with the background estimated from data through an event mixing technique. The top-quark mass is measured to be mt = 173.5 ± 0.7 (stat.) ± 1.3 (syst.) GeV.