28,176 research outputs found

    Experience of Indonesia

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    Capital movements ; Monetary policy ; International finance

    Absence of conventional quantum phase transitions in itinerant systems with disorder

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    Effects of disorder are examined in itinerant systems close to quantum critical points. We argue that spin fluctuations associated with the long-range part of the RKKY interactions generically induce non-Ohmic dissipation due to rare disorder configurations. This dissipative mechanism is found to destabilize quantum Griffiths phase behavior in itinerant systems with arbitrary symmetry of the order parameter, leading to the formation of a "cluster glass" phase preceding uniform ordering.Comment: 4+epsilon pages, 1 figure. Phys. Rev. Lett., in press (2005

    Electron-polaron--electron-polaron bound states in mass-gap graphene-like planar quantum electrodynamics: ss-wave bipolarons

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    A Lorentz invariant version of a mass-gap graphene-like planar quantum electrodynamics, the parity-preserving U(1)Ă—U(1)U(1)\times U(1) massive QED3_3, exhibits attractive interaction in low-energy electron-polaron--electron-polaron ss-wave scattering, favoring quasiparticles bound states, the ss-wave bipolarons.Comment: 6 pages, two figures, references adde

    Quasinormal modes of plane-symmetric black holes according to the AdS/CFT correspondence

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    The electromagnetic and gravitational quasinormal spectra of (3+1)(3+1)-dimensional plane-symmetric anti-de Sitter black holes are analyzed in the context of the AdS/CFT correspondence. According to such a correspondence, the electromagnetic and gravitational quasinormal frequencies of these black holes are associated respectively to the poles of retarded correlation functions of RR-symmetry currents and stress-energy tensor in the holographically dual conformal field theory: the (2+1)(2+1)-dimensional N=8\mathcal{N}=8 super-Yang-Mills theory. The connection between AdS black holes and the corresponding field theory is used to unambiguously fix the boundary conditions that enter the proper definition of quasinormal modes. Such a procedure also helps one to decide, among the various different possibilities, what are the appropriate gauge-invariant quantities one should use in order to correctly describe the electromagnetic and gravitational blackhole perturbations. These choices imply in different dispersion relations for the quasinormal modes when compared to some of the results in the literature. In particular, the long-distance, low-frequency limit of dispersion relations presents the characteristic hydrodynamic behavior of a conformal field theory with the presence of diffusion, shear, and sound wave modes. There is also a family of purely damped electromagnetic modes which tend to the bosonic Matsubara frequencies in the long-wavelength regime.Comment: 39 pages; added references; corrected typos; changed content in section
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