89,785 research outputs found

    New line-interactive UPS system with DSP-based active power-line conditioning

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    Quasiparticle Interference on the Surface of the Topological Insulator Bi2_2Te3_3

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    The quasiparticle interference of the spectroscopic imaging scanning tunneling microscopy has been investigated for the surface states of the large gap topological insulator Bi2_2Te3_3 through the T-matrix formalism. Both the scalar potential scattering and the spin-orbit scattering on the warped hexagonal isoenergy contour are considered. While backscatterings are forbidden by time-reversal symmetry, other scatterings are allowed and exhibit strong dependence on the spin configurations of the eigenfunctions at k points over the isoenergy contour. The characteristic scattering wavevectors found in our analysis agree well with recent experiment results.Comment: 5 pages, 2 figures, Some typos are correcte

    Exclusive Hadronic D Decays to eta' and eta

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    Hadronic decay modes D0(Kˉ0,Kˉ0)η,ηD^0\to(\bar K^0, \bar K^{*0})\eta,\eta' and (D+,Ds+)(π+,ρ+)η,η(D^+,D_s^+)\to(\pi^+,\rho^+)\eta,\eta' are studied in the generalized factorization approach. Form factors for (D,Ds+)(η,η)(D,D_s^+)\to(\eta,\eta') transitions are carefully evaluated by taking into account the wave function normalization of the eta and eta'. The predicted branching ratios are generally in agreement with experiment except for D0Kˉ0η,D+π+ηD^0\to\bar K^0\eta', D^+\to\pi^+\eta and Ds+ρ+ηD_s^+\to\rho^+\eta'; the calculated decay rates for the first two decay modes are too small by an order of magnitude. We show that the weak decays D0Kπ+D^0\to K^-\pi^+ and D+K+Kˉ0D^+\to K^+\bar K^0 followed by resonance-induced final-state interactions (FSI), which are amenable technically, are able to enhance the branching ratios of D0Kˉ0ηD^0\to\bar K^0\eta' and D+π+ηD^+\to\pi^+\eta dramatically without affecting the agreement between theory and experiment for D0Kˉ0ηD^0\to\bar K^0\eta and D+π+ηD^+\to\pi^+\eta'. We argue that it is difficult to understand the observed large decay rates of Ds+ρ+ηD_s^+\to \rho^+\eta' and ρ+η\rho^+\eta simultaneously; FSI, W-annihilation and the production of excess eta' from gluons are not helpful in this regard. The large discrepancy between the factorization hypothesis and experiment for the ratio of Ds+ρ+ηD_s^+\to\rho^+ \eta' and Ds+ηe+νD_s^+\to\eta' e^+\nu remains as an enigma.Comment: 15 pages, 1 figure, to appear in Phys. Rev. D. Form factors for D to eta and eta' transitions are slightly change

    Strength distribution of repeatedly broken chains

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    We determine the probability distribution of the breaking strength for chains of N links, which have been produced by repeatedly breaking a very long chain.Comment: 4 pages, 1 figur

    Bridgeness: A Local Index on Edge Significance in Maintaining Global Connectivity

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    Edges in a network can be divided into two kinds according to their different roles: some enhance the locality like the ones inside a cluster while others contribute to the global connectivity like the ones connecting two clusters. A recent study by Onnela et al uncovered the weak ties effects in mobile communication. In this article, we provide complementary results on document networks, that is, the edges connecting less similar nodes in content are more significant in maintaining the global connectivity. We propose an index named bridgeness to quantify the edge significance in maintaining connectivity, which only depends on local information of network topology. We compare the bridgeness with content similarity and some other structural indices according to an edge percolation process. Experimental results on document networks show that the bridgeness outperforms content similarity in characterizing the edge significance. Furthermore, extensive numerical results on disparate networks indicate that the bridgeness is also better than some well-known indices on edge significance, including the Jaccard coefficient, degree product and betweenness centrality.Comment: 10 pages, 4 figures, 1 tabl

    Chirally symmetric but confining dense and cold matter

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    The folklore tradition about the QCD phase diagram is that at the chiral restoration phase transition at finite density hadrons are deconfined and there appears the quark matter. We address this question within the only known exactly solvable confining and chirally symmetric model. It is postulated within this model that there exists linear Coulomb-like confining interaction. The chiral symmetry breaking and the quark Green function are obtained from the Schwinger-Dyson (gap) equation while the color-singlet meson spectrum results from the Bethe-Salpeter equation. We solve this model at T=0 and finite chemical potential μ\mu and obtain a clear chiral restoration phase transition at the critical value \mu_{cr}. Below this value the spectrum is similar to the previously obtained one at \mu = 0. At \mu > \mu_{cr} the quarks are still confined and the physical spectrum consists of bound states which are arranged into a complete set of exact chiral multiplets. This explicitly demonstrates that a chirally symmetric matter consisting of confined but chirally symmetric hadrons at finite chemical potential is also possible in QCD. If so, there must be nontrivial implications for astrophysics.Comment: 7 pp; the paper has been expanded to make some technical details more clear; 3 new figures have been added. To appear in PR
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