Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Spin Stiffness and the Transverse Susceptibility of the Half-filled
  Hubbard Model   The $T=0$ spin stiffness $\rho _{s}$ and the transverse susceptibility $\chi
_{\perp }$ of the square lattice half-filled Hubbard model are calculated as a
function of the Hubbard parameter ratio $U/t$ by series expansions around the
Ising limit. We find that the calculated spin-stiffness, transverse
susceptibility, and sublattice magnetization for the Hubbard model smoothly
approach the Heisenberg values for large $U/t$. The results are compared for
different $U/t$ with RPA and other numerical studies.

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The categories of this paper are: eess
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The categories of this paper are: astro-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: econ
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The categories of this paper are: cs
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The categories of this paper are: funct-an
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The categories of this paper are: alg-geom
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The categories of this paper are: nucl-th
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The categories of this paper are: adap-org
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The categories of this paper are: q-bio
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The categories of this paper are: nlin
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The categories of this paper are: math
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The categories of this paper are: chem-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-th