Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Optical-conductivity sum rule in cuprates and unconventional charge
  density waves: a short review   We begin with an overview of the experimental results for the temperature and
doping dependences of the optical-conductivity spectral weight in cuprate
superconductors across the whole phase diagram. Then we discuss recent attempts
to explain the observed behavior of the spectral weight using reduced and full
models with unconventional $d_{x^2-y^2}$ charge-density waves.

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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: hep-lat
2
The categories of this paper are: math
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The categories of this paper are: q-alg
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The categories of this paper are: econ
15
The categories of this paper are: nucl-ex
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The categories of this paper are: plasm-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: supr-con
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The categories of this paper are: eess
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The categories of this paper are: math-ph
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The categories of this paper are: stat
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The categories of this paper are: hep-ex
3
The categories of this paper are: physics
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The categories of this paper are: astro-ph