Search for heavy bottomlike quarks decaying to an electron or muon and jets in pp collisions at √s = 1.96 TeV.
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 4.8 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.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
Abstract:
This Letter reports a measurement of the top quark mass, Mtop, in data from pp¯ collisions at s=1.96 TeV corresponding to 2.7 fb−1 of integrated luminosity at the Fermilab Tevatron using the CDF II detector. Events with the lepton+jets topology are selected. An unbinned likelihood is constructed based on the dependence of the lepton transverse momentum, PT, on Mtop. A maximum likelihood fit to the data yields a measured mass Mtop=176.9±8.0stat±2.7syst GeV/c2. In this measurement, the contribution by the jet energy scale uncertainty to the systematic error is negligible. The result provides an important consistency test for other Mtop measurements where explicit use of the jet energy is made for deriving the top quark mass.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.Search for a heavy gauge boson W' in the final state with an electron and large missing transverse energy in pp collisions at s=7 TeV
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 698:1 (2011) 21-39
Abstract:
A search for a heavy gauge boson W' has been conducted by the CMS experiment at the LHC in the decay channel with an electron and large transverse energy imbalance ETmiss, using proton-proton collision data corresponding to an integrated luminosity of 36 pb-1. No excess above standard model expectations is seen in the transverse mass distribution of the electron- ETmiss system. Assuming standard-model-like couplings and decay branching fractions, a W' boson with a mass less than 1.36 TeV/c2 is excluded at 95% confidence level. © 2011 CERN.Measurement of b hadron lifetimes in exclusive decays containing a J/ψ in pp collisions at √s=1.96 TeV.
Phys Rev Lett 106:12 (2011) 121804