35,348 research outputs found
Chapman-Enskog expansion of the Boltzmann equation and its diagrammatic interpretation
We perform a Chapman-Enskog expansion of the Boltzmann equation keeping up to
quadratic contributions. We obtain a generalized nonlinear Kubo formula, and a
set of integral equations which resum ladder and extended ladder diagrams. We
show that these two equations have exactly the same structure, and thus provide
a diagrammatic interpretation of the Chapman-Enskog expansion of the Boltzmann
equation, up to quadratic order.Comment: 5 pages, 2 figures in eps, talk given at XXXI International Symposium
on Multiparticle Dynamics, Sept 1-7, 2001, Datong China. URL
http://ismd31.ccnu.edu.cn
Energy bands and Landau levels of ultracold fermions in the bilayer honeycomb optical lattice
We investigate the spectrum and eigenstates of ultracold fermionic atoms in
the bilayer honeycomb optical lattice. In the low energy approximation, the
dispersion relation has parabolic form and the quasiparticles are chiral. In
the presence of the effective magnetic field, which is created for the system
with optical means, the energy spectrum shows an unconventional Landau level
structure. Furthermore, the experimental detection of the spectrum is proposed
with the Bragg scattering techniques.Comment: To appear in Journal of Modern Optic
Equilibrium and Non-Equilibrium Hard Thermal Loop Resummation in the Real Time Formalism
We investigate the use of the hard thermal loop (HTL) resummation technique
in non-equilibrium field theory. We use the Keldysh representation of the real
time formalism (RTF). We derive the HTL photon self energy and the resummed
photon propagator. We show that no pinch singularities appear in the
non-equilibrium HTL effective propagator. We discuss a possible regularization
mechanism for these singularities at higher orders. As an example of the
application of the HTL resummation method within the RTF we discuss the damping
rate of a hard electron.Comment: 23 pages, REVTEX, 5 PostScript figures, revised version to be
published in Eur. Phys. J.
Four-Point Spectral Functions and Ward Identities in Hot QED
We derive spectral representations for the different components of the
4-point function at finite temperature in the real time formalism in terms of
five real spectral densities. We explicitly calculate all these functions in
QED in the hard thermal loop approximation. The Ward identities obeyed by the
1-loop 3- and 4-point functions in real time and their spectral functions are
derived. We compare our results with those derived previously in the
imaginary-time formalism for retarded functions in hot QCD, and we discuss the
generalization of our results to non-equilibrium situations.Comment: 16 pages in Revtex with 3 figures, dense version, a typo correcte
The Dynamical Yang-Baxter Relation and the Minimal Representation of the Elliptic Quantum Group
In this paper, we give the general forms of the minimal matrix (the
elements of the -matrix are numbers) associated with the Boltzmann
weights of the interaction-round-a-face (IRF) model and the minimal
representation of the series elliptic quantum group given by Felder
and Varchenko. The explicit dependence of elements of -matrices on spectral
parameter are given. They are of five different forms (A(1-4) and B). The
algebra for the coefficients (which do not depend on ) are given. The
algebra of form A is proved to be trivial, while that of form B obey
Yang-Baxter equation (YBE). We also give the PBW base and the centers for the
algebra of form B.Comment: 23 page
q-deformed Supersymmetric t-J Model with a Boundary
The q-deformed supersymmetric t-J model on a semi-infinite lattice is
diagonalized by using the level-one vertex operators of the quantum affine
superalgebra . We give the bosonization of the boundary
states. We give an integral expression of the correlation functions of the
boundary model, and derive the difference equations which they satisfy.Comment: LaTex file 18 page
Spin-current injection and detection in strongly correlated organic conductor
Spin-current injection into an organic semiconductor
film induced by the spin
pumping from an yttrium iron garnet (YIG) film. When magnetization dynamics in
the YIG film is excited by ferromagnetic or spin-wave resonance, a voltage
signal was found to appear in the
film.
Magnetic-field-angle dependence measurements indicate that the voltage signal
is governed by the inverse spin Hall effect in
. We found that the
voltage signal in the /YIG
system is critically suppressed around 80 K, around which magnetic and/or glass
transitions occur, implying that the efficiency of the spin-current injection
is suppressed by fluctuations which critically enhanced near the transitions
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