28,083 research outputs found

    Light-Cone Distribution Amplitudes of Light JPC=2−−J^{PC}=2^{--} Tensor Mesons in QCD

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    We present a study for two-quark light-cone distribution amplitudes for the 13D21^3D_2 light tensor meson states with quantum number JPC=2−−J^{PC}=2^{--}. Because of the G-parity, the chiral-even two-quark light-cone distribution amplitudes of this tensor meson are antisymmetric under the interchange of momentum fractions of the quark and antiquark in the SU(3) limit, while the chiral-odd ones are symmetric. The asymptotic leading-twist LCDAs with the strange quark mass correction are shown. We estimate the relevant parameters, the decay constants fTf_T and fT⊥f_T^\perp, and first Gegenbauer moment a1⊥a_1^\perp, by using the QCD sum rule method. These parameters play a central role in the investigation of BB meson decaying into the 2−−2^{--} tensor mesons.Comment: 18 pages, 3 Figure

    Light-Cone Distribution Amplitudes of Light JPC=2−−J^{PC}=2^{--} Tensor Mesons in QCD

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    We present a study for two-quark light-cone distribution amplitudes for the 13D21^3D_2 light tensor meson states with quantum number JPC=2−−J^{PC}=2^{--}. Because of the G-parity, the chiral-even two-quark light-cone distribution amplitudes of this tensor meson are antisymmetric under the interchange of momentum fractions of the quark and antiquark in the SU(3) limit, while the chiral-odd ones are symmetric. The asymptotic leading-twist LCDAs with the strange quark mass correction are shown. We estimate the relevant parameters, the decay constants fTf_T and fT⊥f_T^\perp, and first Gegenbauer moment a1⊥a_1^\perp, by using the QCD sum rule method. These parameters play a central role in the investigation of BB meson decaying into the 2−−2^{--} tensor mesons.Comment: 18 pages, 3 Figure

    Tau Polarizations in the Three-body Slepton Decays with Stau as the NLSP

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    In the gauge-mediated supersymmetry breaking models with scalar tau as the next-to-lightest supersymmetric particle, a scalar lepton may decay dominantly into its superpartner, tau lepton, and the lightest scalar tau particle. We give detailed formulas for the three-body decay amplitudes and the polarization asymmetry of the outgoing tau lepton . We find that the tau polarizations are sensitive to the model parameters such as the stau mixing angle, the neutralino to slepton mass ratio and the neutralino mixing effect.Comment: 13 pages, 5 figures, RevTe

    Economics of polysilicon processes

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    Techniques are being developed to provide lower cost polysilicon material for solar cells. Existing technology which normally provides semiconductor industry polysilicon material is undergoing changes and also being used to provide polysilicon material for solar cells. Economics of new and existing technologies are presented for producing polysilicon. The economics are primarily based on the preliminary process design of a plant producing 1,000 metric tons/year of silicon. The polysilicon processes include: Siemen's process (hydrogen reduction of trichlorosilane); Union Carbide process (silane decomposition); and Hemlock Semiconductor process (hydrogen reduction of dichlorosilane). The economics include cost estimates of capital investment and product cost to produce polysilicon via the technology. Sensitivity analysis results are also presented to disclose the effect of major paramentes such as utilities, labor, raw materials and capital investment

    Directed flow as effect of transient matter rotation in hadron and nucleus collisions

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    We discuss directed flow introduced for description of nucleus collisions and consider its possible behavior in hadronic and nuclei reactions due to rotation of the transient matter.Comment: 18 pages, 6 figure

    Chapman-Enskog expansion about nonequilibrium states: the sheared granular fluid

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    The Chapman-Enskog method of solution of kinetic equations, such as the Boltzmann equation, is based on an expansion in gradients of the deviations fo the hydrodynamic fields from a uniform reference state (e.g., local equilibrium). This paper presents an extension of the method so as to allow for expansions about \emph{arbitrary}, far-from equilibrium reference states. The primary result is a set of hydrodynamic equations for studying variations from the arbitrary reference state which, unlike the usual Navier-Stokes hydrodynamics, does not restrict the reference state in any way. The method is illustrated by application to a sheared granular gas which cannot be studied using the usual Navier-Stokes hydrodynamics.Comment: 23 pages, no figures. Submited to PRE Replaced to correct misc. errors Replaced to correct misc. errors, make notation more consistant, extend discussio

    Deep shower interpretation of the cosmic ray events observed in excess of the Greisen-Zatsepin-Kuzmin energy

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    We consider the possibility that the ultra-high-energy cosmic ray flux has a small component of exotic particles which create showers much deeper in the atmosphere than ordinary hadronic primaries. It is shown that applying the conventional AGASA/HiRes/Auger data analysis procedures to such exotic events results in large systematic biases in the energy spectrum measurement. SubGZK exotic showers may be mis-reconstructed with much higher energies and mimick superGZK events. Alternatively, superGZK exotic showers may elude detection by conventional fluorescence analysis techniques.Comment: 22 pages, 5 figure

    Superconductivity and Cobalt Oxidation State in Metastable Na(x)CoO(2-delta)*yH2O (x ~ 1/3; y ~ 4x)

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    We report the synthesis and superconducting properties of a metastable form of the known superconductor NaxCoO2*yH2O (x ~ 1/3, y ~ 4x). Instead of using the conventional bromine-acetonitrile mixture for sodium deintercalation, we use an aqueous bromine solution. Using this method, we oxidize the sample to a point that the sodium cobaltate becomes unstable, leading to formation of other products if not controlled. This compound has the same structure as the reported superconductor, yet it exhibits a systematic variation of the superconducting transition temperature (Tc) as a function of time. Immediately after synthesis, this compound is not a superconductor, even though it contains appropriate amounts of sodium and water. The samples become superconducting with low Tc values after ~ 90 h. Tc continually increases until it reaches a maximum value (4.5 K) after about 260 h. Then Tc drops drastically, becoming non-superconducting approximately 100 h later. Corresponding time-dependent neutron powder diffraction data shows that the changes in superconductivity exhibited by the metastable cobaltate correspond to slow formation of oxygen vacancies in the CoO2 layers. In effect, the formation of these defects continually reduces the cobalt oxidation state causing the sample to evolve through its superconducting life cycle. Thus, the dome-shaped superconducting phase diagram is mapped as a function of cobalt oxidation state using a single sample. The width of this dome based on the formal oxidation state of cobalt is very narrow - approximately 0.1 valence units wide. Interestingly, the maximum Tc in NaxCoO2*yH2O occurs when the cobalt oxidation state is near 3.5. Thus, we speculate that the maximum Tc occurs near the charge ordered insulating state that correlates with the average cobalt oxidation state of 3.5.Comment: 22 pages, 9 figures, 1 tabl
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