Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Sine-Gordon Theory for the Equation of State of Classical Hard-Core
  Coulomb systems. III Loopwise Expansion   We present an exact field theoretical representation of an ionic solution
made of charged hard spheres. The action of the field theory is obtained by
performing a Hubbard-Stratonovich transform of the configurational Boltzmann
factor. It is shown that the Stillinger-Lovett sum rules are satisfied if and
only if all the field correlation functions are short range functions. The mean
field, Gaussian and two-loops approximations of the theory are derived and
discussed. The mean field approximation for the free energy constitutes a
rigorous lower bound for the exact free energy, while the mean field pressure
is an upper bound. The one-loop order approximation is shown to be identical
with the random phase approximation of the theory of liquids. Finally, at the
two-loop order and in the pecular case of the restricted primitive model, one
recovers results obtained in the framework of the mode expansion theory.

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The categories of this paper are: math-ph
2
The categories of this paper are: math
33
The categories of this paper are: plasm-ph
25
The categories of this paper are: patt-sol
1
The categories of this paper are: cs
3
The categories of this paper are: physics
12
The categories of this paper are: nucl-th
31
The categories of this paper are: ao-sci
23
The categories of this paper are: solv-int
32
The categories of this paper are: atom-ph
18
The categories of this paper are: econ
30
The categories of this paper are: q-alg
16
The categories of this paper are: stat
34
The categories of this paper are: chem-ph
22
The categories of this paper are: chao-dyn
21
The categories of this paper are: adap-org