Measurement of the top-quark mass with all-jets final states in pp collisions at 7 TeV

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 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 $m_t = 173.5 \pm 0.7 (stat.) \pm 1.3 (syst.)$ GeV.