Measurement of the $t\bar{t}$ production cross section in the all-jet final state in pp collisions at $\sqrt{s}$ = 7 TeV

Abstract

A measurement is presented of the $t\bar{t}$ cross section $(\sigma_{t\bar{t}})$ in proton-proton collisions at a centre-of-mass energy of 7 TeV, in the all-jet final state that contains at least six jets, two of which are tagged as likely originating from b quarks. The data correspond to an integrated luminosity of 3.54 inverse femtobarns, collected with the CMS detector at the LHC. The cross section is determined through an unbinned maximum likelihood fit of contributions from background and t t-bar signal to the reconstructed mass spectrum of t t-bar candidates in the data, in which events are subjected to a kinematic fit assuming a $t\bar{t} \to W^+ b W^- \bar{b} \to 6$ jets hypothesis. The measurement yields $\sigma_{t\bar{t}} = 139 \pm 10 (stat.) \pm 26 (syst.) \pm 3 (lum.)$ pb, a result consistent with those obtained in other $t\bar{t}$ decay channels, as well as with predictions of the standard model.