Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Aspects of Non-Equilibrium Dynamics in Quantum Field Theory   This work is devoted to the study of relaxation--dissipation processes in
systems described by Quantum Field Theory. In the first part, I focus on the
phi^4 scalar quantum field theory in finite volume in the large N limit. I find
that the zero-mode quantum fluctuations cannot grow macroscopically large
starting from microscopic initial conditions, while the long-wavelength
fluctuations do scale with the linear size of the system, signalling dynamical
infrared properties quite different from the equilibrium ones. I also introduce
a non-gaussian Hartree-Fock approximation (tdHF) and I derive the mean-field
coupled time-dependent Schroedinger equations for the modes of the scalar
field. The dynamical evolution of a uniform condensate is studied in a further
controlled gaussian approximation, for N=1. Results similar to the large N case
show an internal inconsistency of this approximation. I also study the dynamics
of the system in infinite volume in the broken symmetry phase. The data show
that the fixed points of the evolution cover at most the classically metastable
part of the static effective potential. I finally study the dynamical evolution
for the O(N+1) nonlinear sigma model in 1+1 dimensions in the large N limit. I
first of all verify that the large coupling limit of the O(N+1) phi^4 model,
which renders the model non linear, commutes with the large N limit, so that
the O(infty) nonlinear sigma model is uniquely defined. I then study the
evolution of several observables, like the spectrum of produced particles,
finding no evidence for parametric resonance. I conclude with some remarks on
the ``state of art'' in gauge theories and some comments about the open issues
in the subject.

30
The categories of this paper are: q-alg
9
The categories of this paper are: nlin
15
The categories of this paper are: nucl-ex
22
The categories of this paper are: chao-dyn
37
The categories of this paper are: supr-con
34
The categories of this paper are: chem-ph
33
The categories of this paper are: plasm-ph
28
The categories of this paper are: alg-geom
17
The categories of this paper are: q-fin
23
The categories of this paper are: solv-int
14
The categories of this paper are: math-ph
27
The categories of this paper are: comp-gas
10
The categories of this paper are: q-bio
26
The categories of this paper are: bayes-an
13
The categories of this paper are: quant-ph
32
The categories of this paper are: atom-ph