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
Forward production of charged pions with incident protons on nuclear targets at the CERN Proton Synchrotron
Physical Review C - Nuclear Physics 80:3 (2009)
Abstract:
Measurements of the double-differential π± production cross section in the range of momentum 0.5□p□8.0 GeV/c and angle 0.025□θ□0.25 rad in collisions of protons on beryllium, carbon, nitrogen, oxygen, aluminum, copper, tin, tantalum, and lead are presented. The data were taken with the large-acceptance HAdRon Production (HARP) detector in the T9 beamline of the CERN Proton Synchrotron. Incident particles were identified by an elaborate system of beam detectors. Thin targets of 5% of a nuclear interaction length were used. The tracking and identification of the produced particles were performed using the forward system of the HARP experiment. Results are obtained for the double-differential cross sections d2σ/dpdΩ mainly at four incident proton beam momenta (3, 5, 8, and 12 GeV/c). Measurements are compared with the GEANT4 and MARS Monte Carlo generators. A global parametrization is provided as an approximation of all the collected datasets, which can serve as a tool for quick yield estimates. © 2009 The American Physical Society.Search for muon-neutrino to electron-neutrino transitions in MINOS
ArXiv 0909.4996 (2009)