55,102 research outputs found

    Size dependence of second-order hyperpolarizability of finite periodic chain under Su-Schrieffer-Heeger model

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    The second hyperpolarizability γN(−3ωω,ω,ω)\gamma_N(-3\omega\omega,\omega,\omega) of NN double-bond finite chain of trans-polyactylene is analyzed using the Su-Schrieffer-Heeger model to explain qualitative features of the size-dependence behavior of γN\gamma_N. Our study shows that γN/N\gamma_N/N is {\it nonmonotonic} with NN and that the nonmonotonicity is caused by the dominant contribution of the intraband transition to γN\gamma_N in polyenes. Several important physical effects are discussed to reduce quantitative discrepancies between experimental and our resultsComment: 3 figures, 1 tabl

    A new and finite family of solutions of hydrodynamics. Part I: Fits to pseudorapidity distributions

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    We highlight some of the interesting properties of a new and finite, exact family of solutions of 1 + 1 dimensional perfect fluid relativistic hydrodynamics. After reviewing the main properties of this family of solutions, we present the formulas that connect it to the measured rapidity and pseudo-rapidity densities and illustrate the results with fits to p+p collisions at 8 TeV and Pb+Pb collisions at sNN=5.02\sqrt{s_{NN}} = 5.02 TeV.Comment: Invited talk of T. Csorgo at the WPCF 2018 conference in Cracow, Poland, May 22-26, 2018. Submitted to Acta Physica Polonica

    The Equation of State and Quark Number Susceptibility in Hard-Dense-Loop Approximation

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    Based on the method proposed in [ H. S. Zong, W. M. Sun, Phys. Rev. \textbf{D 78}, 054001 (2008)], we calculate the equation of state (EOS) of QCD at zero temperature and finite quark chemical potential under the hard-dense-loop (HDL) approximation. A comparison between the EOS under HDL approximation and the cold, perturbative EOS of QCD proposed by Fraga, Pisarski and Schaffner-Bielich is made. It is found that the pressure under HDL approximation is generally smaller than the perturbative result. In addition, we also calculate the quark number susceptibility (QNS) at finite temperature and finite chemical potential under hard-thermal/dense-loop (HTL/HDL) approximation and compare our results with the corresponding ones in the previous literature.Comment: 12 pages, 3 figure

    Thermal rectification in asymmetric U-shaped graphene flakes

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    In this paper, we study the thermal rectification in asymmetric U-shaped graphene flakes by using nonequilibrium molecular dynamics simulations. The graphene flakes are composed by a beam and two arms. It is found that the heat flux runs preferentially from the wide arm to the narrow arm which indicates a strong rectification effect. The dependence of the rectification ratio upon the heat flux, the length and the width of the beam, the length and width of the two arms are studied. The result suggests a possible route to manage heat dissipation in U-shaped graphene based nanoelectronic devices.Comment: 3 pages, 4 figure
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