Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Comparison of the $\pi$ and $\Delta$ operator approximations for the
  two-dimensional t-J model   We compare the spectra of the new $\pi$ operator of the SO(5) theory and the
conventional $\Delta$ operator for the two-dimensional t-J model. We also
calculate the weight transferred to the two-hole ground state from half-filling
by these operators. We find that the spectra of these operators are quite
similar and the weight for the $\pi$ operator is smaller than the weight for
the $\Delta$ operator. We argue that the two-dimensional t-J model does not
have a good approximate SO(5) symmetry claimed in Ref. 1.

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The categories of this paper are: chem-ph
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The categories of this paper are: comp-gas
5
The categories of this paper are: gr-qc
11
The categories of this paper are: hep-lat
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The categories of this paper are: dg-ga
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The categories of this paper are: q-alg
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The categories of this paper are: q-fin
6
The categories of this paper are: astro-ph
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The categories of this paper are: eess
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The categories of this paper are: plasm-ph
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The categories of this paper are: ao-sci
14
The categories of this paper are: math-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: quant-ph
1
The categories of this paper are: cs
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The categories of this paper are: nlin