Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Effective action and collective modes in quasi-one-dimensional
  spin-density-wave systems   We derive the effective action describing the long-wavelength low-energy
collective modes of quasi-one-dimensional spin-density-wave (SDW) systems,
starting from the Hubbard model within weak coupling approximation. The
effective action for the spin-wave mode corresponds to an anisotropic
non-linear sigma model together with a Berry phase term. We compute the spin
stiffness and the spin-wave velocity. We also obtain the effective action for
the sliding mode (phason) taking into account the density fluctuations from the
outset and in presence of a weak external electromagnetic field. This leads to
coupled equations for the phase of the SDW condensate and the charge density
fluctuations. We also calculate the conductivity and the density-density
correlation function.

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The categories of this paper are: funct-an
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The categories of this paper are: hep-ph
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The categories of this paper are: acc-phys
34
The categories of this paper are: chem-ph
9
The categories of this paper are: nlin
14
The categories of this paper are: math-ph
27
The categories of this paper are: comp-gas
18
The categories of this paper are: econ
33
The categories of this paper are: plasm-ph
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The categories of this paper are: adap-org
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-lat
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The categories of this paper are: physics
10
The categories of this paper are: q-bio
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The categories of this paper are: cs
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The categories of this paper are: q-fin