Measurement of the Top Quark Mass and p anti-p --> tt-bar Cross Section in the All-Hadronic Mode with the CDF II Detector

We present a measurement of the top quark mass and of the top-antitop pair production cross section using p anti-p data collected with the CDF II detector at the Tevatron Collider at the Fermi National Accelerator Laboratory and corresponding to an integrated luminosity of 2.9 fb-1. We select events with six or more jets satisfying a number of kinematical requirements imposed by means of a neural network algorithm. At least one of these jets must originate from a b quark, as identified by the reconstruction of a secondary vertex inside the jet. The mass measurement is based on a likelihood fit incorporating reconstructed mass distributions representative of signal and background, where the absolute jet energy scale (JES) is measured simultaneously with the top quark mass. The measurement yields a value of 174.8 +/- 2.4(stat + JES)+1.2_-1.0(syst) GeV/c2, where the uncertainty from the absolute jet energy scale is evaluated together with the statistical uncertainty. The procedure measures also the amount of signal from which we derive a cross section, sigma_tt-bar = 7.2 +/- 0.5(stat) +/- 1.0(syst) +/- 0.4(lum) pb, for the measured values of top quark mass and JES.