Observation of the Ωb- baryon and measurement of the properties of the Ξb- and Ωb- baryons
Physical Review D - Particles, Fields, Gravitation and Cosmology 80:7 (2009)
Abstract:
We report the observation of the bottom, doubly-strange baryon Ωb- through the decay chain Ωb-→J/ψΩ-, where J/ψ→μ+μ-, Ω-→ΛK-, and Λ→pπ-, using 4.2fb-1 of data from pp̄ collisions at s=1.96TeV, and recorded with the Collider Detector at Fermilab. A signal is observed whose probability of arising from a background fluctuation is 4.0×10-8, or 5.5 Gaussian standard deviations. The Ωb- mass is measured to be 6054.4±6. 8(stat)±0.9(syst)MeV/c2. The lifetime of the Ωb- baryon is measured to be 1.13-0.40+0.53(stat)±0.02(syst)ps. In addition, for the Ξb- baryon we measure a mass of 5790.9±2.6(stat)±0.8(syst)MeV/c2 and a lifetime of 1.56-0.25+0.27(stat)±0.02(syst)ps. Under the assumption that the Ξb- and Ωb- are produced with similar kinematic distributions to the Λb0 baryon, we find σ(Ξb-)B(Ξb-→J/ψΞ-) σ(Λb0)B(Λb0→J/ψΛ)=0.167-0.025+0.037(stat) ±0.012(syst) and σ(Ωb-)B(Ωb-→J/ψΩ-) σ(Λb0)B(Λb0→J/ψΛ)=0.045-0.012+0.017(stat) ±0.004(syst) for baryons produced with transverse momentum in the range of 6-20GeV/c. © 2009 The American Physical Society.Precision measurement of the X(3872) mass in J/ψπ+π- decays
Physical Review Letters 103:15 (2009)
Abstract:
We present an analysis of the mass of the X(3872) reconstructed via its decay to J/ψπ+π- using 2.4fb-1 of integrated luminosity from pp̄ collisions at s=1.96TeV, collected with the CDF II detector at the Fermilab Tevatron. The possible existence of two nearby mass states is investigated. Within the limits of our experimental resolution the data are consistent with a single state, and having no evidence for two states we set upper limits on the mass difference between two hypothetical states for different assumed ratios of contributions to the observed peak. For equal contributions, the 95% confidence level upper limit on the mass difference is 3.6MeV/c2. Under the single-state model the X(3872) mass is measured to be 3871.61±0.16(stat)±0. 19(syst)MeV/c2, which is the most precise determination to date. © 2009 The American Physical Society.Publisher’s Note: Search for hadronic decays of W and Z bosons in photon events in pp¯ collisions at s=1.96 TeV [Phys. Rev. D 80, 052011 (2009)]
Physical Review D American Physical Society (APS) 80:7 (2009) 079901
New techniques in the search for Z' bosons and other neutral resonances
Modern Physics Letters A 24:30 (2009) 2387-2403
Abstract:
The search for neutral resonances at the energy frontier has a long and illustrious history, resulting in multiple discoveries. The canonical search scans the reconstructed invariant mass distribution of identified fermion pairs. Two recent analyses from the CDF experiment at the Fermilab Tevatron have applied novel methods to resonance searches. One analysis uses simulated templates to fit the inverse mass distribution of muon pairs, a quantity with approximately constant resolution for momenta measured with a tracking detector. The other analysis measures the angular distribution of electron pairs as a function of dielectron mass, gaining sensitivity over a probe of the mass spectrum alone. After reviewing several models that predict new neutral resonances, we discuss these CDF analyses and potential future applications. © 2009 World Scientific Publishing Company.Search for hadronic decays of W and Z bosons in photon events in pp̄ collisions at s=1.96TeV
Physical Review D - Particles, Fields, Gravitation and Cosmology 80:5 (2009)