20,033 research outputs found

    Polarization Dependence of Raman Spectra in Strained Graphene

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    The polarization dependences of the G, D, and 2D (G′') bands in Raman spectra at graphene bulk and edge are examined theoretically. The 2D and D bands have different selection rules at bulk and edge. At bulk, the 2D band intensity is maximum when the polarization of the scattered light is parallel to that of incident light, whereas the D band intensity does not have a polarization dependence. At edge, the 2D and D bands exhibit a selection rule similar to that of the G band proposed in a previous paper. We suggest that a constraint equation on the axial velocity caused by the graphene edge is essential for the dependence of the G band on the crystallographic orientation observed in the bulk of strained graphene. This is indicative of that the pseudospin and valleyspin in the bulk of graphene can not be completely free from the effect of surrounding edge. The status of the experiments on the G and D bands at the graphene edge is mentioned.Comment: 11 pages, 3 figure

    Gap Condition and Self-Dualized N=4{\cal N}=4 Super Yang-Mills Theory for ADE Gauge Group on K3

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    We try to determine the partition function of N=4{\cal N}=4 super Yang-Mills theoy for ADE gauge group on K3 by self-dualizing our previous ADE partition function. The resulting partition function satisfies gap condition.Comment: 17 page

    Excited nucleon spectrum from lattice QCD with maximum entropy method

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    We study excited states of the nucleon in quenched lattice QCD with the spectral analysis using the maximum entropy method. Our simulations are performed on three lattice sizes 163×3216^3\times 32, 243×3224^3\times 32 and 323×3232^3\times 32, at β=6.0\beta=6.0 to address the finite volume issue. We find a significant finite volume effect on the mass of the Roper resonance for light quark masses. After removing this systematic error, its mass becomes considerably reduced toward the direction to solve the level order puzzle between the Roper resonance N′(1440)N'(1440) and the negative-parity nucleon N∗(1535)N^*(1535).Comment: Lattice2003(spectrum), 3 pages, 4 figure

    Bayesian approach to the first excited nucleon state in lattice QCD

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    We present preliminary results from the first attempt to reconstruct the spectral function in the nucleon and Δ\Delta channels from lattice QCD data using the maximum entropy method (MEM). An advantage of the MEM analysis is to enable us to access information of the excited state spectrum. Performing simulations on two lattice volumes, we confirm the large finite size effect on the first excited nucleon state in the lighter quark mass region.Comment: Lattice2002(spectrum), Latex with espcrc2.sty, 3 pages, 3 figure

    Effect of surface roughness on friction behaviour of steel under boundary lubrication

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    The friction behaviour of grinded and polished surfaces was evaluated by using a reciprocal sliding tester under lubrication with PAO, PAO + ZnDTP and PAO + ZnDTP + MoDTC. Friction coefficients on the smooth surfaces showed higher values compared to those on the rough surfaces. For lubrication incorporating PAO and PAO + ZnDTP + MoDTC, friction coefficients on both the smoothest and the roughest surfaces decreased with sliding time. On the other hand, friction coefficients between these extremes decreased with sliding time. In this paper, the effects of surface roughness on friction behaviour are discussed
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