158,914 research outputs found

    Finite-Size Effects in the Ï•4\phi^{4} Field Theory Above the Upper Critical Dimension

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    We demonstrate that the standard O(n) symmetric ϕ4\phi^{4} field theory does not correctly describe the leading finite-size effects near the critical point of spin systems on a dd-dimensional lattice with d>4d > 4. We show that these finite-size effects require a description in terms of a lattice Hamiltonian. For n→∞n \to \infty and n=1n=1 explicit results are given for the susceptibility and for the Binder cumulant. They imply that recent analyses of Monte-Carlo results for the five-dimensional Ising model are not conclusive.Comment: 4 pages, latex, 1 figur

    On a class of reductions of Manakov-Santini hierarchy connected with the interpolating system

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    Using Lax-Sato formulation of Manakov-Santini hierarchy, we introduce a class of reductions, such that zero order reduction of this class corresponds to dKP hierarchy, and the first order reduction gives the hierarchy associated with the interpolating system introduced by Dunajski. We present Lax-Sato form of reduced hierarchy for the interpolating system and also for the reduction of arbitrary order. Similar to dKP hierarchy, Lax-Sato equations for LL (Lax fuction) due to the reduction split from Lax-Sato equations for MM (Orlov function), and the reduced hierarchy for arbitrary order of reduction is defined by Lax-Sato equations for LL only. Characterization of the class of reductions in terms of the dressing data is given. We also consider a waterbag reduction of the interpolating system hierarchy, which defines (1+1)-dimensional systems of hydrodynamic type.Comment: 15 pages, revised and extended, characterization of the class of reductions in terms of the dressing data is give

    Phase transition in site-diluted Josephson junction arrays: A numerical study

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    We numerically investigate the intriguing effects produced by random percolative disorder in two-dimensional Josephson-junction arrays. By dynamic scaling analysis, we evaluate critical temperatures and critical exponents with high accuracy. It is observed that, with the introduction of site-diluted disorder, the Kosterlitz-Thouless phase transition is eliminated and evolves into a continuous transition with power-law divergent correlation length. Moreover, genuine depinning transition and creep motion are studied, evidence for distinct creep motion types is provided. Our results not only are in good agreement with the recent experimental findings, but also shed some light on the relevant phase transitions.Comment: 7 pages, 8 figures, Phys. Rev. B (in press

    Quantum criticality in a Mott pn-junction in an armchair carbon nanotube

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    In an armchair carbon nanotube pn junction the p- and n- regions are separated by a region of a Mott insulator, which can backscatter electrons only in pairs. We predict a quantum-critical behavior in such a pn junction. Depending on the junction's built-in electric field E, its conductance G scales either to zero or to the ideal value G=4e^2/h as the temperature T is lowered. The two types of the G(T) dependence indicate the existence, at some special value of E, of an intermediate quantum critical point with a finite conductance G<4e^2/h. This makes the pn junction drastically different from a simple barrier in a Luttinger liquid.Comment: 5 pages, 1 figur

    On surface plasmon polariton wavepacket dynamics in metal-dielectric heterostructures

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    The WKB equations for dynamics of the surface plasmon polariton (SPP) wavepacket are studied. The dispersion law for the SPP in the metal-dielectric heterostructure with varying thickness of a perforated dielectric layer is rigorously calculated and investigated using the scattering matrix method. Two channels of the SPP wavepacket optical losses related to the absorption in a metal and to the SPP leakage are analyzed. It is shown that change of the dielectric layer thickness acts on the SPP as an external force leading to evolution of its quasimomentum and to the wavepacket reversal or even to the optical Bloch oscillations (BO). Properties of these phenomena are investigated and discussed. Typical values of the BO amplitude are about tens of microns and the period is around tens or hundreds of femtoseconds.Comment: 12 pages, 5 figure

    Y(4260) --> gamma + X(3872) in the diquarkonium picture

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    The observed Y(4260)\to \gamma + X(3872) decay is a natural consequence of the diquark-antidiquark description of Y and X resonances. In this note we attempt an estimate of the transition rate, \Gamma_{\rm rad}, by a non-relativistic calculation of the electric dipole term of a diquarkonium bound state. We compute \Gamma_{\rm rad} for generic composition values of the isospin of X and Y. Specializing to I=0 for X(3872), we find \Gamma_{\rm rad}= 496~keV for Y(4260) with I=0 and \Gamma_{\rm rad}= 179~keV for I=1. Combining with BESIII data, we derive upper bounds to B(Y\to J/\Psi+\pi+\pi) and to \Gamma(Y\to \mu^+ \mu^-). We expect to confront these results with forthcoming data from electron-positron and hadron colliders.Comment: references added and minor corrections, 11 pages, 1 figur

    Demonstration of optically modulated dispersion forces

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    We report the first experiment on the optical modulation of dispersion forces through a change of the carrier density in a Si membrane. For this purpose a high-vacuum based atomic force microscope and excitation light pulses from an Ar laser are used. The experimental results are compared with two theoretical models. The modulation of the dispersion force will find applications in optomechanical micromachines.Comment: 7 pages, 3 figures, opex3.sty is used, text has been made in accordance with the final version to appear in Optics express, 3 misprints are correcte
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