Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the theory of phase transitions in binary fluid mixtures   The microscopic approach to the description of the phase behaviour and
critical phenomena in binary fluid mixtures is proposed. It is based on the
method of collective variables with a reference system. The physical nature of
the order parameter in a binary mixture is discussed. The basic density measure
(Ginsburg-Landau-Wilson Hamiltonian) is obtained in the collective variable
phase space which contains the variable connected with the order parameter of
the system. It is shown that the problem can be reduced to the 3D Ising model
in an external field.

25
The categories of this paper are: patt-sol
7
The categories of this paper are: hep-th
19
The categories of this paper are: eess
22
The categories of this paper are: chao-dyn
30
The categories of this paper are: q-alg
12
The categories of this paper are: nucl-th
33
The categories of this paper are: plasm-ph
11
The categories of this paper are: hep-lat
31
The categories of this paper are: ao-sci
10
The categories of this paper are: q-bio
26
The categories of this paper are: bayes-an
15
The categories of this paper are: nucl-ex
23
The categories of this paper are: solv-int
6
The categories of this paper are: astro-ph
5
The categories of this paper are: gr-qc
17
The categories of this paper are: q-fin