11,939 research outputs found

    SU(2) gluon propagator on a coarse anisotropic lattice

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    We calculated the SU(2) gluon propagator in Landau gauge on an anisotropic coarse lattice with the improved action. The standard and the improved scheme are used to fix the gauge in this work. Even on the coarse lattice the lattice gluon propagator can be well described by a function of the continuous momentum. The effect of the improved gauge fixing scheme is found not to be apparent. Based on the Marenzoni's model, the mass scale and the anomalous dimension are extracted and can be reasonably extrapolated to the continuum limit with the values α0.3\alpha\sim 0.3 and M600MeVM\sim 600MeV. We also extract the physical anisotropy ξ\xi from the gluon propagator due to the explicit ξ\xi dependence of the gluon propagator.Comment: LaTeX, 14 pages including 4 ps figure

    On Two-Body Decays of A Scalar Glueball

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    We study two body decays of a scalar glueball. We show that in QCD a spin-0 pure glueball (a state only with gluons) cannot decay into a pair of light quarks if chiral symmetry holds exactly, i.e., the decay amplitude is chirally suppressed. However, this chiral suppression does not materialize itself at the hadron level such as in decays into π+π\pi^+\pi^- and K+KK^+K^-, because in perturbative QCD the glueball couples to two (but not one) light quark pairs that hadronize to two mesons. Using QCD factorization based on an effective Lagrangian, we show that the difference of hadronization into ππ\pi\pi and KKKK already leads to a large difference between Br(π+π){\rm Br} (\pi^+\pi^-) and Br(K+K){\rm Br}(K^+K^-), even the decay amplitude is not chirally suppressed. Moreover, the small ratio of R=Br(ππ)/Br(KKˉ)R={\rm Br}(\pi\pi)/{\rm Br}(K\bar K) of f0(1710)f_0(1710) measured in experiment does not imply f0(1710)f_0(1710) to be a pure glueball. With our results it is helpful to understand the partonic contents if Br(ππ){\rm Br}(\pi\pi) or Br(KKˉ){\rm Br}(K\bar K) is measured reliably.Comment: revised versio

    Local spin fluctuations in iron-based superconductors: 77Se and 87Rb NMR measurements of Tl0.47Rb0.34Fe1.63Se2

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    We report nuclear magnetic resonance (NMR) studies of the intercalated iron selenide superconductor (Tl, Rb)y_{y}Fe2x_{2-x}Se2_2 (Tc=32T_c = 32 K). Single-crystal measurements up to 480 K on both 77^{77}Se and 87^{87}Rb nuclei show a superconducting phase with no magnetic order. The Knight shifts KK and relaxation rates 1/T1T1/T_1T increase very strongly with temperature above TcT_c, before flattening at 400 K. The quadratic TT-dependence and perfect proportionality of both KK and 1/T1T1/T_1T data demonstrate their origin in paramagnetic moments. A minimal model for this pseudogap-like response is not a missing density of states but two additive contributions from the itinerant electronic and local magnetic components, a framework unifying the KK and 1/T1T1/T_1 T data in many iron-based superconductors

    MC-Simulation of the Transverse Double Spin Asymmetry for RHIC

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    Using {\sc Sphinx tt}, a new MC simulation program for transverse polarized nucleon--nucleon scattering based on {\sc Pythia~5.6}, we calculate the transverse double spin asymmetry ATTA^{TT} in the Drell-Yan process. If one assumes (quite arbitrarily) that the transversity parton distribution δq(x,Q2)\delta q(x,Q^2) equals the helicity distribution Δq(x,Q2)\Delta q(x,Q^2) at some low Q02Q_0^2 scale, the resulting asymmetry is of order 1\%. In this case is ATTA^{TT} would hardly be be measurable with PHENIX at RHIC.Comment: 17 pages, 5 figure

    Three-photon absorption in water-soluble ZnS nanocrystals

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    We report on large three-photon absorption (3PA) in glutathione-capped ZnS semiconductor nanocrystals (NCs), determined by both Z-scan and transient transmission techniques with 120-fs laser pulses. The monodispersed, water-soluble ZnS NCs are synthesized by a modified protocol with a mean diameter of 2.5 nm. Their 3PA cross-section is determined to be around 2.7x10^-78 cm^6s^2photon^-2 at an optimal wavelength of commercial Ti:sapphire femtosecond lasers. This value is nearly one order of magnitude greater than that of CdS NCs, and four to five orders of magnitude higher than those of the previously reported common UV fluorescent dyes.Comment: 15 pages, 4 figure

    Lifting method to analyze pipeline deformation

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    Lifting is to use lifting equipment to lift components and install them to the designated position. On the main structure, lifting equipment is used to transport the flue and transport the sectional flue to the designated position. Certain deformation will occur during the lifting operation of the flue due to its force condition, but it is not known whether it is elastic deformation or plastic deformation. Therefore, this paper analyzes the stress and strain of the flue during operation by finite element method, and observes and analyzes the influence of plastic deformation on the whole flue

    Deformation analysis of running electric hoist

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    According to the practical engineering application, three-dimensional modeling of electric hoist and I-beam track is carried out, and the model is simplified to determine the electric hoist load, roller acceleration and speed, and the Abaqus software is used to simulate, analyze the simulation results, observe the actual maximum load under the track stress and strain to meet the requirements, calculate the allowable stress, Observe whether it exceeds the allowable stress and whether plastic deformation occurs. If the numerical simulation results of stress and strain are within the safety requirements, the project can be implemented
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