Measurement of the ttbar production cross section in proton-antiproton   collisions at sqrt{s}=1.96 TeV using multijet events
  We present two measurements of the ttbar production cross section in collisions of protons and antiprotons at sqrt{s}=1.96 TeV. We analyze a dataset of 310+/-20 pb-1 collected with the CDF2 detector. In the first measurement, we select events with six to eight jets, at least one of which having a displaced secondary vertex, little or no missing transverse energy and optimized kinematical criteria consistent with the ttbar all-hadronic decay channel. In the second measurement, we select events with four or more jets, at least one of which having a displaced secondary vertex, high missing transverse energy, and optimized kinematical criteria consistent with the decay of ttbar to tau+jets. The averaged ttbar production cross section, determined from six different measurements using the CDF2 detector in the dilepton, lepton+jets and all-hadronic decay channels, is also calculated to be sigma_ttbar=7.1+/-0.6 (stat)+/-0.7(syst)+/-0.4 (lumi) pb, in agreement with the prediction of the standard model. 
Lucio Cerrito (for the CDF Collaboration)