15,038 research outputs found

    The BIOEXPLOIT Project

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    The EU Framework 6 Integrated Project BIOEXPLOIT concerns the exploitation of natural plant biodiversity for the pesticide-free production of food. It focuses on the pathogens Phytophthora infestans, Septoria tritici, Blumeria graminis, Puccinia spp. and Fusarium spp. and on the crops wheat, barley, tomato and potato. The project commenced in October 2005, comprises 45 laboratories in 12 countries, and is carried out by partners from research institutes, universities, private companies and small-medium enterprises. The project has four strategic objectives covered in eight sub-projects. These objectives relate to (i) understanding the molecular components involved in durable disease resistance, (ii) exploring and exploiting the natural biodiversity in disease resistance, (iii) accelerating the introduction of marker-assisted breeding and genetic engineering in the EU plant breeding industry, and (iv) coordinating and integrating resistance breeding research, providing training in new technologies, disseminating the results, and transferring knowledge and technologies to the industry

    Effective theory of NN interactions in a separable representation

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    We consider the effective field theory of the NN system in a separable representation. The pionic part of the effective potential is included nonperturbatively and approximated by a separable potential. The use of a separable representation allows for the explicit solution of the Lippmann-Schwinger equation and a consistent renormalization procedure. The phase shifts in the 1S0^1S_0 channel are calculated to subleading order.Comment: 7 page

    Disentangling Intertwined Embedded States and Spin Effects in Light-Front Quantization

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    Naive light-front quantization, carried out by a light-front energy integration of covariant amplitudes, is not guaranteed to generate the corresponding Feynman amplitudes. In an explicit example we show that the nonvalence contribution to the minus-component of the EM current of a meson with fermion constituents has a persistent end-point singularity. Only after this term is subtracted, the result is covariant and satisfies current conservation. If the spin-1/2 constituents are replaced by spin zero ones, the singularity does not occur and the result is, without any adjustment, identical to the Feynman amplitude. Numerical estimates of valence and nonvalence contributions are presented for the cases of fermion and boson constituents.Comment: 17 pages and 9 figure

    Strong coupling constant from bottomonium fine structure

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    From a fit to the experimental data on the bbˉb\bar{b} fine structure, the two-loop coupling constant is extracted. For the 1P state the fitted value is αs(μ1)=0.33±0.01(exp)±0.02(th)\alpha_s(\mu_1) = 0.33 \pm 0.01(exp)\pm 0.02 (th) at the scale μ1=1.8±0.1\mu_1 = 1.8 \pm 0.1 GeV, which corresponds to the QCD constant Λ(4)(2−loop)=338±30\Lambda^{(4)}(2-loop) = 338 \pm 30 MeV (n_f = 4) and αs(MZ)=0.119±0.002.Forthe2Pstatethevalue\alpha_s(M_Z) = 0.119 \pm 0.002. For the 2P state the value \alpha_s(\mu_2) = 0.40 \pm 0.02(exp)\pm 0.02(th)atthescale at the scale \mu_2 = 1.02 \pm 0.2GeVisextracted,whichissignificantlylargerthaninthepreviousanalysisofFulcher(1991)andHalzen(1993),butabout30smallerthanthevaluegivenbystandardperturbationtheory.Thisvalue GeV is extracted, which is significantly larger than in the previous analysis of Fulcher (1991) and Halzen (1993), but about 30% smaller than the value given by standard perturbation theory. This value \alpha_s(1.0) \approx 0.40canbeobtainedintheframeworkofthebackgroundperturbationtheory,thusdemonstratingthefreezingof can be obtained in the framework of the background perturbation theory, thus demonstrating the freezing of \alpha_s.Therelativisticcorrectionsto. The relativistic corrections to \alpha_s$ are found to be about 15%.Comment: 18 pages LaTe

    The leptonic widths of high ψ\psi-resonances in unitary coupled-channel model

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    The leptonic widths of high ψ\psi-resonances are calculated in a coupled-channel model with unitary inelasticity, where analytical expressions for mixing angles between (n+1)\,^3S_1 and n\,^3D_1 states and probabilities ZiZ_i of the ccˉc\bar c component are derived. Since these factors depend on energy (mass), different values of mixing angles θ(ψ(4040))=27.7∘\theta(\psi(4040))=27.7^\circ and θ(ψ(4160))=29.5∘\theta(\psi(4160))=29.5^\circ, Z1 (ψ(4040))=0.76Z_1\,(\psi(4040))=0.76, and Z2 (ψ(4160))=0.62Z_2\,(\psi(4160))=0.62 are obtained. It gives the leptonic widths Γee(ψ(4040))=Z1 1.17=0.89\Gamma_{ee}(\psi(4040))=Z_1\, 1.17=0.89~keV, Γee(ψ(4160))=Z2 0.76=0.47\Gamma_{ee}(\psi(4160))=Z_2\, 0.76=0.47~keV in good agreement with experiment. For ψ(4415)\psi(4415) the leptonic width Γee(ψ(4415))= 0.55\Gamma_{ee}(\psi(4415))=~0.55~keV is calculated, while for the missing resonance ψ(4510)\psi(4510) we predict M(ψ(4500))=(4515±5)M(\psi(4500))=(4515\pm 5)~MeV and Γee(ψ(4510))≅0.50\Gamma_{ee}(\psi(4510)) \cong 0.50~keV.Comment: 10 pages, 6 references corrected, some new material adde

    Higher excitations of the DD and DsD_s mesons

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    The masses of higher D(nL)D(nL) and Ds(nL)D_s(nL) excitations are shown to decrease due to the string contribution, originating from the rotation of the QCD string itself: it lowers the masses by 45 MeV for L=2(n=1)L=2 (n=1) and by 65 MeV for L=3(n=1)L=3 (n=1). An additional decrease ∼100\sim 100 MeV takes place if the current mass of the light (strange) quark is used in a relativistic model. For Ds(1 3D3)D_s(1\,{}^3D_3) and Ds(2P1H)D_s(2P_1^H) the calculated masses agree with the experimental values for Ds(2860)D_s(2860) and Ds(3040)D_s(3040), and the masses of D(2 1S0)D(2\,{}^1S_0), D(2 3S1)D(2\,{}^3S_1), D(1 3D3)D(1\,{}^3D_3), and D(1D2)D(1D_2) are in agreement with the new BaBar data. For the yet undiscovered resonances we predict the masses M(D(2 3P2))=2965M(D(2\,{}^3P_2))=2965 MeV, M(D(2 3P0))=2880M(D(2\,{}^3P_0))=2880 MeV, M(D(1 3F4))=3030M(D(1\,{}^3F_4))=3030 MeV, and M(Ds(1 3F2))=3090M(D_s(1\,{}^3F_2))=3090 MeV. We show that for L=2,3L=2,3 the states with jq=l+1/2j_q=l+1/2 and jq=l−1/2j_q=l-1/2 (J=lJ=l) are almost completely unmixed (ϕ≃−1∘\phi\simeq -1^\circ), which implies that the mixing angles θ\theta between the states with S=1 and S=0 (J=LJ=L) are θ≈40∘\theta\approx 40^\circ for L=2 and ≈42∘\approx 42^\circ for L=3.Comment: 22 pages, no figures, 4 tables Two references and corresponding discussion adde
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