4,060 research outputs found
A Diagrammatic Interpretation of the Boltzmann Equation
We study nonlinear response in weakly coupled nonequilibrium theory
in the context of both classical transport theory and real time quantum field
theory, based on a generalized Kubo formula which we derive. A novel connection
between these two approaches is established which provides a diagrammatic
interpretation of the Boltzmann equation.Comment: 5 pages in RevTex with 4 Postscript figure
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
Spontaneous Symmetry Breaking for Scalar QED with Non-minimal Chern-Simons Coupling
We investigate the two-loop effective potential for both minimally and
non-minimally coupled Maxwell-Chern-Simons theories. The non-minimal gauge
interaction represents the magnetic moment interaction between a charged scalar
and the electromagnetic field. In a previous paper we have shown that the two
loop effective potential for this model is renormalizable with an appropriate
choice of the non-minimal coupling constant. We carry out a detailed analysis
of the spontaneous symmetry breaking induced by radiative corrections. As long
as the renormalization point for all couplings is chosen to be the true minimum
of the effective potential, both models predict the presence of spontaneous
symmetry breaking. Two loop corrections are small compared to the one loop
result, and thus the symmetry breaking is perturbatively stable.Comment: Revtex 25 pages, 9 figure
Spontaneous Scale Symmetry Breaking in 2+1-Dimensional QED at Both Zero and Finite Temperature
A complete analysis of dynamical scale symmetry breaking in 2+1-dimensional
QED at both zero and finite temperature is presented by looking at solutions to
the Schwinger-Dyson equation. In different kinetic energy regimes we use
various numerical and analytic techniques (including an expansion in large
flavour number). It is confirmed that, contrary to the case of 3+1 dimensions,
there is no dynamical scale symmetry breaking at zero temperature, despite the
fact that chiral symmetry breaking can occur dynamically. At finite
temperature, such breaking of scale symmetry may take place.Comment: 12 pages, no figures, uses RevTeX4-bet
KMS conditions for 4-point Green functions at finite temperature
We study the 4-point function in the Keldysh formalism of the closed time
path formulation of real time finite temperature field theory.
We derive the KMS conditions for these functions and discuss the number of
4-point functions that are independent. We define a set of `physical' functions
which are linear combinations of the usual Keldysh functions. We show that
these functions satisfy simple KMS conditions. In addition, we consider a set
of integral equations which represent a resummation of ladder graphs. We show
that these integral equations decouple when one uses the physical functions
that we have defined. We discuss the generalization of these results to QED.Comment: 17 pages in Revtex with 2 figure
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
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