Measurement of the ttbar production cross section in the fully hadronic decay channel in pp collisions at 7 TeV

This note presents a first measurement of the top quark pair production cross section in the fully hadronic decay channel at a center-of-mass energy of $\sqrt{s}=7~\TeV$ using data corresponding to an integrated luminosity of 1.09~\fbinv taken with the CMS detector. The cross section is determined from an unbinned maximum likelihood fit to the reconstructed top quark mass. The reconstruction of \ttbar candidates is performed after a cut-based event selection using a kinematic fit. A data-driven technique is used to estimate the dominant background from QCD multijet production. The cross section measurement yields \mbox{$\sigma_{\ttbar} = 136 \pm 20 \text{ (stat.)} \pm 40 \text{ (sys.)} \pm 8 \text{ (lumi.)}$~pb}. This result is consistent with measurements in other decay channels and with the Standard Model prediction.