Measurement of $t\bar{t}$ production in the all-hadronic channel in 1.02~$\mathrm{fb}^{-1}$ of pp collisions at $\sqrt{s}=7$ TeV with the ATLAS detector

We present a measurement of the $t\bar{t}$ production cross-section in the all-hadronic channel with the ATLAS detector. The analysis is performed using 1.02~$\mathrm{fb}^{-1}$ of $pp$ collisions produced at the LHC with a centre-of-mass energy of $\sqrt{s}=$~7~TeV and recorded with the ATLAS detector. After selecting events passing a multi-jet trigger and kinematic requirements, we require events to have two reconstructed jets identified as $b$-jets. After preselection, an {\it Event Mixing} method is used to model the kinematics of a higher jet-multiplicity \mj sample from a lower jet-multiplicity one, depleted in signal events. The total $t\bar{t}$~cross-section is then extracted using a binned likelihood fit of the $\chi^2$ from a kinematic fit assuming the $t\bar{t}$ event hypothesis and measured to be $\sigma_{t\bar{t}}$~=~167~$\pm$~18~(stat.)~$\pm$~78~(syst.)~$\pm$~6~(lum.)~pb, consistent with the Standard Model prediction. As a cross-check of this analysis, an alternative one using a method exploiting $b$-tagging information and the centrality of the events, the {\it ABCD} method, is also discussed.