Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Charge and Spin Gap Formation in Exactly Solvable Hubbard Chains with
  Long-Rang Hopping   We discuss the transition from a metal to charge or spin insulating phases
characterized by the opening of a gap in the charge or spin excitation spectra,
respectively. These transitions are addressed within the context of two exactly
solvable Hubbard and tJ chains with long range, $1/r$ hopping. We discuss the
specific heat, compressibility, and magnetic susceptibility of these models as
a function of temperature, band filling, and interaction strength. We then use
conformal field theory techniques to extract ground state correlation
functions. Finally, by employing the $g$-ology analysis we show that the charge
insulator transition is accompanied by an infinite discontinuity in the Drude
weight of the electrical conductivity. While the magnetic properties of these
models reflect the genuine features of strongly correlated electron systems,
the charge transport properties, especially near the Mott-Hubbard transition,
display a non-generic behavior.

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The categories of this paper are: nlin
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The categories of this paper are: mtrl-th
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The categories of this paper are: cs
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The categories of this paper are: patt-sol
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The categories of this paper are: comp-gas
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The categories of this paper are: quant-ph
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The categories of this paper are: math
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The categories of this paper are: stat
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The categories of this paper are: plasm-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: nucl-th
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The categories of this paper are: chem-ph
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The categories of this paper are: astro-ph
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The categories of this paper are: solv-int
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The categories of this paper are: gr-qc
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The categories of this paper are: ao-sci