Search for heavy bottomlike quarks decaying to an electron or muon and jets in pp collisions at √s = 1.96 TeV.
Physical review letters 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 4.8 fb(-1). We observe events consistent with background expectation, calculate upper limits on the b' pair-production cross section (σ(bb')) ≲30 fb for m(b') > 375 GeV/c2), and exclude m(b') < 372 GeV/c2 at 95% confidence level assuming a 100% branching ratio of b' to tW.Observation of Bs0→J/ψK*(892)0 and Bs0→J/ψKS0 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 pp̄ collisions at √s=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/ψ→μ+μ - decays. We reconstruct a Bs0→J/ψK*(892)0 signal with K*(892)0→K+π-, observing a yield of 151±25 events with a statistical significance of 8.0σ. We also reconstruct a Bs0→J/ψKS0 signal with KS0→π+π-, observing a yield of 64±14 events with a statistical significance of 7.2σ. From these yields, we extract the branching ratios B(Bs0→J/ψK*(892)0)=(8. 3±3.8)×10-5 and B(Bs0→J/ψK0)=(3.5±0.8) ×10-5, 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/ψ in pp̄ collisions at √s=1.96TeV
Physical Review Letters 106:12 (2011)
Abstract:
We report on a measurement of b-hadron lifetimes in the fully reconstructed decay modes B+→J/ψK+, B0→J/ ψK*(892)0, B0→J/ψKs0, and Λb0→J/ψΛ0 using data corresponding to an integrated luminosity of 4.3fb-1, collected by the CDF II detector at the Fermilab Tevatron. The measured lifetimes are τ(B+)=[1.639±0.009(stat)±0.009(syst)] ps, τ(B0)=[1.507±0.010(stat)±0.008(syst)]ps, and τ(Λb0)=[1.537±0.045(stat)±0.014(syst)]ps. The lifetime ratios are τ(B+)/τ(B0)=[1.088±0.009(stat)±0. 004(syst)] and τ(Λb0)/τ(B0)=[1.020±0.030(stat)±0. 008(syst)]. These are the most precise determinations of these quantities from a single experiment. © 2011 American Physical Society.Search for high mass resonances decaying to Muon pairs in √s=1.96TeV pp̄ collisions
Physical Review Letters 106:12 (2011)
Abstract:
We present a search for a new narrow, spin-1, high mass resonance decaying to μ+μ-+X, using a matrix-element-based likelihood and a simultaneous measurement of the resonance mass and production rate. In data with 4.6fb-1 of integrated luminosity collected by the CDF detector in pp̄ collisions at √s=1960GeV, the most likely signal cross section is consistent with zero at 16% confidence level. We therefore do not observe evidence for a high mass resonance and place limits on models predicting spin-1 resonances, including M>1071GeV/c2 at 95% confidence level for a Z′ boson with the same couplings to fermions as the Z boson. © 2011 American Physical Society.Observation of Bs0→J/ψK*(892)0 and Bs0→J/ψKS0 decays
Physical Review D American Physical Society (APS) 83:5 (2011) 052012