116 research outputs found

    Measurement of forward-backward asymmetry and wilson coefficients in B -> K(*)l(+)l(-)

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    We report the first measurement of the forward-backward asymmetry and the ratios of Wilson coefficients A(9)/A(7) and A(10)/A(7) in B -> K(*)l(+)l(-), where l represents an electron or a muon. We find evidence for the forward-backward asymmetry with a significance of 3.4 sigma. The results are obtained from a data sample containing 386x10(6) (B) over bar pairs that were collected on the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider

    Estimating retention benchmarks for salvage logging to protect biodiversity

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    S.T. was supported by the Humboldt-Foundation and by the MOST (Ministry of Science and Technology) Taiwan Research Fellowship to work with A.C. at National Tsing Hua University, Taiwan. S.T. received funds from the Gregor Louisoder Environmental Foundation. A.B.L. received funds from the Humboldt-Foundation.Forests are increasingly affected by natural disturbances. Subsequent salvage logging, a widespread management practice conducted predominantly to recover economic capital, produces further disturbance and impacts biodiversity worldwide. Hence, naturally disturbed forests are among the most threatened habitats in the world, with consequences for their associated biodiversity. However, there are no evidence-based benchmarks for the proportion of area of naturally disturbed forests to be excluded from salvage logging to conserve biodiversity. We apply a mixed rarefaction/extrapolation approach to a global multi-taxa dataset from disturbed forests, including birds, plants, insects and fungi, to close this gap. We find that 75 ± 7% (mean ± SD) of a naturally disturbed area of a forest needs to be left unlogged to maintain 90% richness of its unique species, whereas retaining 50% of a naturally disturbed forest unlogged maintains 73 ± 12% of its unique species richness. These values do not change with the time elapsed since disturbance but vary considerably among taxonomic groups.Open Access funding enabled and organized by Projekt DEA

    Using an insect mushroom body circuit to encode route memory in complex natural environments

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    Ants, like many other animals, use visual memory to follow extended routes through complex environments, but it is unknown how their small brains implement this capability. The mushroom body neuropils have been identified as a crucial memory circuit in the insect brain, but their function has mostly been explored for simple olfactory association tasks. We show that a spiking neural model of this circuit originally developed to describe fruitfly (Drosophila melanogaster) olfactory association, can also account for the ability of desert ants (Cataglyphis velox) to rapidly learn visual routes through complex natural environments. We further demonstrate that abstracting the key computational principles of this circuit, which include one-shot learning of sparse codes, enables the theoretical storage capacity of the ant mushroom body to be estimated at hundreds of independent images

    Observation of direct CP violation in B-0 ->pi(+)pi(-) decays and model-independent constraints on the quark-mixing angle phi(2)

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    We report a new measurement of the time-dependent CP-violating parameters in B-0 ->pi(+)pi(-) decays with 535x10(6) B (B) over bar pairs collected with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider operating at the Upsilon(4S) resonance. We find 1464 +/- 65 B-0 ->pi(+)pi(-) events and measure the CP-violating parameters S-pi pi=-0.61 +/- 0.10(stat)+/- 0.04(syst) and A(pi pi)=+0.55 +/- 0.08(stat)+/- 0.05(syst). We observe large direct CP violation with a significance greater than 5 standard deviations for any S-pi pi value. Using isospin relations, we measure the Cabibbo-Kobayashi-Maskawa quark-mixing matrix angle phi(2)=(97 +/- 11)degrees for the solution consistent with the standard model and exclude the range 11 degrees <phi(2)< 79 degrees at the 95% confidence level

    Experimental constraints on the spin and parity of the Lambda(c)(2880)(+)

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    We report the results of several studies of the Lambda(+)(c)pi(+)pi X- final state in continuum e(+)e(-) annihilation data collected by the Belle detector. An analysis of angular distributions in Lambda(c)(2880)(+)->Sigma(c)(2455)(0,++)pi(+,-) decays strongly favors a Lambda(c)(2880)(+) spin assignment of 5/ over 3/2 or 1/2. We find evidence for Lambda(c)(2880)(+)->Sigma(c)(2520)(0,++)pi(+,-) decay and measure the ratio of Lambda(c)(2880)(+) partial widths Gamma(Sigma(c)(2520)pi)/Gamma(Sigma(c)(2455)pi)=0.225 +/- 0.062 +/- 0.025. This value favors the Lambda(c)(2880)(+) spin-parity assignment of 5/2(+) over 5/2(-). We also report the first observation of Lambda(c)(2940)(+)->Sigma(c)(2455)(0,++)pi(+,-) decay and measure Lambda(c)(2880)(+) and Lambda(c)(2940)(+) mass and width parameters. These studies are based on a 553 fb(-1) data sample collected at or near the Upsilon(4S) resonance at the KEKB collider

    Measurement of the tau lepton mass and an upper limit on the mass difference between tau(+) and tau(-)

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    The mass of the tau lepton has been measured in the decay mode tau -> 3 pi nu(tau) using a pseudomass technique. The result obtained from 414 fb(-1) of data collected with the Belle detector is M-tau=[1776.61 +/- 0.13(stat)+/- 0.35(sys)] MeV/c(2). The upper limit on the relative mass difference between positive and negative tau leptons is |M-tau(+)-M-tau(-)|/M-tau < 2.8x10(-4) at 90% confidence level
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