28,505 research outputs found
Absence of conventional quantum phase transitions in itinerant systems with disorder
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: -wave bipolarons
A Lorentz invariant version of a mass-gap graphene-like planar quantum
electrodynamics, the parity-preserving massive QED,
exhibits attractive interaction in low-energy
electron-polaron--electron-polaron -wave scattering, favoring quasiparticles
bound states, the -wave bipolarons.Comment: 6 pages, two figures, references adde
Knowledge-based resource management for multifunction radar - A look at scheduling and task prioritization
Quasinormal modes of plane-symmetric black holes according to the AdS/CFT correspondence
The electromagnetic and gravitational quasinormal spectra of
-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 -symmetry currents and stress-energy tensor in the
holographically dual conformal field theory: the -dimensional
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
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