Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Bound Excitons in Sr$_{2}$CuO$_{3}$   We investigated temperature dependent optical spectra of the one-dimensional
chain compound Sr$_{2}$CuO$_{3}$. The charge transfer transition polarized
along the chain direction shows a strongly asymmetric line shape as expected in
one-dimensional extended Hubbard model. At low temperature the charge transfer
peak shows a large blue shift and reveals additional sharp peaks at the gap.
Even though many spectroscopic studies suggest that this material can not have
a bound exciton based on the one-dimensional extended Hubbard model, we
attribute the additional sharp peaks to excitons, which come to exist due to
the long range Coulomb interaction.

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The categories of this paper are: hep-ex
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The categories of this paper are: funct-an
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The categories of this paper are: supr-con
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The categories of this paper are: atom-ph
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The categories of this paper are: q-bio
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The categories of this paper are: alg-geom
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The categories of this paper are: chao-dyn
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The categories of this paper are: ao-sci
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The categories of this paper are: nucl-ex
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The categories of this paper are: chem-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: adap-org
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The categories of this paper are: dg-ga
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The categories of this paper are: bayes-an
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The categories of this paper are: q-alg
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The categories of this paper are: hep-th