Measurement of the ttÌ production cross section with an in situ calibration of b-jet identification efficiency
Physical Review D - Particles, Fields, Gravitation and Cosmology 83:7 (2011)
Abstract:
A measurement of the top-quark pair-production cross section in ppÌ collisions at âs=1.96TeV using data corresponding to an integrated luminosity of 1.12fb-1 collected with the Collider Detector at Fermilab is presented. Decays of top-quark pairs into the final states eΜ+ jets and ΌΜ+ jets are selected, and the cross section and the b-jet identification efficiency are determined using a new measurement technique which requires agreement between the measured cross sections with exactly one and with multiple identified b quarks from the top-quark decays. Assuming a top-quark mass of 175GeV/c2, a cross section of 8.5±0.6(stat)±0. 7(syst)pb is measured. © 2011 American Physical Society.Search for heavy bottomlike quarks decaying to an electron or muon and jets in pp collisions at âs = 1.96ââTeV.
Phys Rev Lett 106:14 (2011) 141803
Abstract:
We report the most sensitive direct search for pair production of fourth-generation bottomlike chiral quarks (b') each decaying promptly to tW. We search for an excess of events with an electron or muon, at least five jets (one identified as due to a b or c quark), and an imbalance of transverse momentum by using data from pp collisions collected by the CDF II detector at Fermilab with an integrated luminosity of 4.8ââfb(-1). We observe events consistent with background expectation, calculate upper limits on the b' pair-production cross section (Ï(bb')) âČ30ââfb for m(b') > 375ââGeV/c2), and exclude m(b') < 372ââGeV/c2 at 95% confidence level assuming a 100% branching ratio of b' to tW.Measurement of the top quark mass in the lepton+jets channel using the lepton transverse momentum
Physics Letters B Elsevier 698:5 (2011) 371-379
Observation of Bs0âJ/ÏK*(892)0 and Bs0âJ/ÏKS0 decays
Physical Review D - Particles, Fields, Gravitation and Cosmology 83:5 (2011)
Abstract:
We report the first observation of two Cabibbo-suppressed decay modes of the Bs0 meson. Using a sample of ppÌ collisions at âs=1.96TeV corresponding to 5.9fb-1 of integrated luminosity collected with the CDF II, the collider detector at the Fermilab Tevatron, we search for new Bs0 decay modes in a sample of events containing J/ÏâÎŒ+ÎŒ - decays. We reconstruct a Bs0âJ/ÏK*(892)0 signal with K*(892)0âK+Ï-, observing a yield of 151±25 events with a statistical significance of 8.0Ï. We also reconstruct a Bs0âJ/ÏKS0 signal with KS0âÏ+Ï-, observing a yield of 64±14 events with a statistical significance of 7.2Ï. From these yields, we extract the branching ratios B(Bs0âJ/ÏK*(892)0)=(8. 3±3.8)Ă10-5 and B(Bs0âJ/ÏK0)=(3.5±0.8) Ă10-5, where statistical, systematic, and fragmentation- fraction uncertainties are included in the combined uncertainty. © 2011 American Physical Society.Measurement of b hadron lifetimes in exclusive decays containing a J/Ï in pp collisions at âs=1.96 TeV.
Phys Rev Lett 106:12 (2011) 121804