5,012 research outputs found

    The Significance of Two Contrasting Sedimentary Environments (the Fringing Coral Reef and the Tidal Mud Flat) Presently in Juxtaposition Along the Southwestern Shore of Moreton Bay, Queensland

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    Fringing coral reefs are developed adjacent to the islands within Moreton Bay, near Dunwich on the western side of North Stradbroke Island, and along the southwestern shores of the bay between Point Halloran and Wellington Point. Between Wellington Point and Cleveland Point reef growth is almost continuous for 10km, but rarely exceeds 5mm in thickness. This reef began to develop approximately 7500 years B.P. upon a seaward-sloping laterite platform. Coral growth did not keep pace with riisng sea-level. Portions of the reef may have reached the intertidal zone about the same time as those reefs at Mud Island where uranium series dates from 4100 to 6000 B.P. have been obtained. Subsequently the back-reef area has been filled with terrigenous and bioclastic sediments. A distinctive tidal flat zonation has been developed. Mangroves have developed in relatively recent times, having first colonized the upper intertidal surface of the reefs (north of Empire Point) or the landward side of beach ridges (shores of Raby Bay). Organic mud produced by the mangroves severely inhibits coral growth and the intertidal surface of the reef now consists of dead Acropora, whereas living corals (Faviidae) are restricted to the subtidal areas. Seaward pro-gradation of the mangroves is very limited, however, landward extension is evident in some places

    Measurement of the semileptonic branching fraction of the B_s meson

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    We report a measurement of the inclusive semileptonic branching fraction of the B_s meson using data collected with the BABAR detector in the center-of-mass energy region above the Υ(4S) resonance. We use the inclusive yield of ϕ mesons and the ϕ yield in association with a high-momentum lepton to perform a simultaneous measurement of the semileptonic branching fraction and the production rate of B_s mesons relative to all B mesons as a function of center-of-mass energy. The inclusive semileptonic branching fraction of the B_s meson is determined to be B(B_s→ℓνX)=9.5_(-2.0)^(+2.5)(stat)_(-1.9)^(+1.1)(syst)%, where ℓ indicates the average of e and μ

    B^0 meson decays to ρ^0K^(*0), f_0K^(*0), and ρ^-K^(*+), including higher K^* resonances

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    We present branching fraction measurements for the decays B^0→ρ^0K^(*0), B^0→f_0K^(*0), and B^0→ρ^-K^(*+), where K^* is an S-wave (Kπ)_0^* or a K^*(892) meson; we also measure B^0→f_0K_2^*(1430)^0. For the K^*(892) channels, we report measurements of longitudinal polarization fractions (for ρ final states) and direct CP violation asymmetries. These results are obtained from a sample of (471.0±2.8)×10^6 BB̅ pairs collected with the BABAR detector at the PEP-II asymmetric-energy e^+e^- collider at the SLAC National Accelerator Laboratory. We observe ρ^0K^*(892)^0, ρ^0(Kπ)_0^(*0), f_0K^*(892)^0, and ρ^-K^*(892)^+ with greater than 5σ significance, including systematics. We report first evidence for f_0(Kπ)_0^(*0) and f_0K_2^*(1430)^0, and place an upper limit on ρ^-(Kπ)_0^(*+). Our results in the K^*(892) channels are consistent with no direct CP violation

    Search for the decay D^0 → γγ and measurement of the branching fraction for D^0 → π^0π^0

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    We search for the rare decay of the D^0 meson to two photons, D^0→γγ, and present a measurement of the branching fraction for a D^0 meson decaying to two neutral pions, B(D^0→π^0π^0). The data sample analyzed corresponds to an integrated luminosity of 470.5  fb^(-1) collected by the BABAR detector at the PEP-II asymmetric-energy e^+e^- collider at SLAC. We place an upper limit on the branching fraction, B(D^0→γγ)<2.2×10^(-6), at 90% confidence level. This limit improves on the existing limit by an order of magnitude. We also find B(D^0→π^0π^0)=(8.4±0.1±0.4±0.3)×10^(-4)

    Observation of the baryonic B decay B̅^0→Λ_c^+Λ̅ K^-

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    We report the observation of the baryonic B decay B̅ ^0→Λ_c^+Λ̅ K^- with a significance larger than 7 standard deviations based on 471×10^6 BB̅ pairs collected with the BABAR detector at the PEP-II storage ring at SLAC. We measure the branching fraction for the decay B̅ ^0→Λ_c^+Λ̅ K^- to be (3.8±0.8_(stat)±0.2_(sys)±1.0_(Λc)^+)×10^(-5). The uncertainties are statistical, systematic, and due to the uncertainty in the Λc+ branching fraction. We find that the Λ_c^+K^- invariant-mass distribution shows an enhancement above 3.5  GeV/c^2

    Search for CP violation in the decay τ-→π-K_S^0(≥0π^0)ν_τ

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    We report a search for CP violation in the decay τ-→π-KS^0(≥0π^0)ντ using a data set of 437×10^6 τ-lepton pairs, corresponding to an integrated luminosity of 476  fb^(-1), collected with the BABAR detector at the PEP-II asymmetric-energy e^+e^- storage rings. The CP-violating decay-rate asymmetry is determined to be (-0.36±0.23±0.11)% approximately 2.8 standard deviations from the standard model prediction of (0.36±0.01)%

    Study of radiative bottomonium transitions using converted photons

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    We use (111±1) million Υ(3S) and (89±1) million Υ(2S) events recorded by the BABAR detector at the PEP-II B-factory at SLAC to perform a study of radiative transitions between bottomonium states using photons that have been converted to e^+e^- pairs by the detector material. We observe Υ(3S)→γ_(χb0,2)(1P) decay, make precise measurements of the branching fractions for χ_(b1,2)(1P,2P)→γΥ(1S) and χ_(b1,2)(2P)→γΥ(2S) decays, and search for radiative decay to the η_b(1S) and η_b(2S) states

    Study of Y(3S,2S) → ηY(1S) and Y(3S,2S) → π^+π^-Y(1S) hadronic transitions

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    We study the Υ(3S,2S)→ηΥ(1S) and Υ(3S,2S)→π^+π^-Υ(1S) transitions with 122×10^6Υ(3S) and 100×10^6Υ(2S) mesons collected by the BABAR detector at the PEP-II asymmetric-energy e^+e^- collider. We measure B[Υ(2S)→ηΥ(1S)]=(2.39±0.31(stat.)±0.14(syst.))×10^(-4) and Γ[Υ(2S)→ηΥ(1S)]/Γ[Υ(2S)→π^+π^-Υ(1S)]=(1.35±0.17(stat.)±0.08(syst.))×10^(-3). We find no evidence for Υ(3S)→ηΥ(1S) and obtain B[Υ(3S)→ηΥ(1S)]<1.0×10^(-4) and Γ[Υ(3S)→ηΥ(1S)]/ Γ[Υ(3S)→π^+π^-Υ(1S)]<2.3×10^(-3) as upper limits at the 90% confidence level. We also provide improved measurements of the Υ(2S)-Υ(1S) and Υ(3S)-Υ(1S) mass differences, 562.170±0.007(stat.)±0.088(syst.)  MeV/c^2 and 893.813±0.015(stat.)±0.107(syst.)  MeV/c^2, respectively

    Branching fraction measurements of the color-suppressed decays B̅^0 to D^((*)0_π^(0), D^((*)0)η, D^((*)0)ω, and D^((*)0)η′ and measurement of the polarization in the decay B̅ 0→D^(*0)ω

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    We report updated branching fraction measurements of the color-suppressed decays B̅ ^(0) → D^(0)π^(0), D^(*0)π^(0), D^(0)η, D^(*0)η, D^(0)ω, D^(*0)ω, D^(0)η′, and D^(*0)η′. We measure the branching fractions (×10^(-4)): B(B̅^0 → D^(0)π^(0)) = 2.69±0.09±0.13, B(B̅^(0) → D^(*0)π^(0)) = 3.05±0.14±0.28, B(B̅^(0) → D^(0)η) = 2.53±0.09±0.11, B(B̅^(0) → D^(*0)η) = 2.69±0.14±0.23, B(B̅^(0) → D^(0)ω) = 2.57±0.11±0.14, B(B̅^(0) → D^(*0)ω) = 4.55±0.24±0.39, B(B̅^(0)→D^(0)η′) = 1.48±0.13±0.07, and B(B̅^(0) → D^(*0)n′) = 1.49±0.22±0.15. We also present the first measurement of the longitudinal polarization fraction of the decay channel D*0ω, fL=(66.5±4.7±1.5)%. In the above, the first uncertainty is statistical and the second is systematic. The results are based on a sample of (454±5)×10^6 BB̅ pairs collected at the Υ(4S) resonance, with the BABAR detector at the PEP-II storage rings at SLAC. The measurements are the most precise determinations of these quantities from a single experiment. They are compared to theoretical predictions obtained by factorization, Soft Collinear Effective Theory (SCET) and perturbative QCD (pQCD). We find that the presence of final state interactions is favored and the measurements are in better agreement with SCET than with pQCD
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