Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The rotationally invariant approximation for the two-dimensional t-J
  model   Using the description in terms of the Hubbard operators hole and spin Green's
functions of the two-dimensional t-J model are calculated in an approximation
which retains the rotation symmetry of the spin susceptibility in the
paramagnetic state and has no predefined magnetic ordering. In this
approximation, Green's functions are represented by continued fractions which
are interrupted with the help of the decoupling corrected by the constraint of
zero site magnetization in the paramagnetic state. Results obtained in this
approach for an undoped 32x32 lattice (the Heisenberg model) and for one hole
in a 4x4 lattice are in good agreement with Monte Carlo and exact
diagonalization data, respectively. In the limit of heavy doping the hole
spectrum described by the obtained formulas acquires features of the spectrum
of weakly correlated excitations.

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The categories of this paper are: ao-sci
27
The categories of this paper are: comp-gas
9
The categories of this paper are: nlin
23
The categories of this paper are: solv-int
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The categories of this paper are: eess
37
The categories of this paper are: supr-con
2
The categories of this paper are: math
21
The categories of this paper are: adap-org
25
The categories of this paper are: patt-sol
34
The categories of this paper are: chem-ph
15
The categories of this paper are: nucl-ex
0
The categories of this paper are: hep-ph
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The categories of this paper are: stat
18
The categories of this paper are: econ
14
The categories of this paper are: math-ph
32
The categories of this paper are: atom-ph