Measurement of the top quark mass and pp̄→tt̄ cross section in the all-hadronic mode with the CDF II detector
Physical Review D - Particles, Fields, Gravitation and Cosmology 81:5 (2010)
Abstract:
We present a measurement of the top quark mass and of the top-antitop (tt̄) pair production cross section using pp̄ data collected with the CDF II detector at the Tevatron Collider at the Fermi National Accelerator Laboratory and corresponding to an integrated luminosity of 2.9fb-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)-1.0+1.2(syst)GeV/c2, where the uncertainty from the absolute jet energy scale is evaluated together with the statistical uncertainty. The procedure also measures the amount of signal from which we derive a cross section, σtt̄=7.2±0.5(stat)±1.0(syst) ±0.4(lum)pb, for the measured values of top quark mass and JES. © 2010 The American Physical Society.Measurement of the Λb0 lifetime in Λb0→Λc+π - decays in pp̄ collisions at √s=1.96TeV
Physical Review Letters 104:10 (2010)
Abstract:
We report a measurement of the lifetime of the Λb0 baryon in decays to the Λc+π- final state in a sample corresponding to 1.1fb-1 collected in pp̄ collisions at √s=1.96TeV by the CDF II detector at the Tevatron collider. Using a sample of about 3000 fully reconstructed Λb0 events we measure τ(Λb0)=1.401±0. 046(stat)±0.035(syst)ps (corresponding to cτ(Λb0)=420. 1±13.7(stat)±10.6(syst)μm, where c is the speed of light). The ratio of this result and the world average B0 lifetime yields τ(Λb0)/τ(B0)=0.918±0.038 (stat) and (syst), in good agreement with recent theoretical predictions. © 2010 The American Physical Society.Search for New Bottomlike Quark Pair Decays QQ¯→(tW∓)(t¯W±) in Same-Charge Dilepton Events
Physical Review Letters American Physical Society (APS) 104:9 (2010) 091801
Search for new bottomlike quark pair decays QQ̄→(tW) (t̄W±) in same-charge dilepton events
Physical Review Letters 104:9 (2010)
Abstract:
We report the most restrictive direct limits on masses of fourth-generation down-type quarks b′, and quarklike composite fermions (B or T5/3), decaying promptly to tW. We search for a significant excess of events with two same-charge leptons (e, μ), several hadronic jets, and missing transverse energy. An analysis of data from pp̄ collisions with an integrated luminosity of 2.7fb-1 collected with the CDF II detector at Fermilab yields no evidence for such a signal, setting mass limits mb ′, mB>338GeV/c2 and mT5/3>365GeV/c2 at 95% confidence level. © 2010 The American Physical Society.Measurement of the top quark mass and pp¯→tt¯ cross section in the all-hadronic mode with the CDF II detector
Physical Review D American Physical Society (APS) 81:5 (2010) 052011