Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ultrafast dynamics of charge density waves in 4Hb-TaSe2 probed by
  femtosecond electron diffraction   The dynamics of the photoinduced commensurate to incommensurate charge
density wave (CDW) phase transition in 4Hb-TaSe2 are investigated by
femtosecond electron diffraction. In the perturbative regime the CDW reforms on
a 150 ps timescale, which is two orders of magnitude slower than in other
transition-metal dichalcogenides. We attribute this to a weak coupling between
the CDW carrying T-layers and thus demonstrate the importance of
three-dimensionality for the existence of CDWs. With increasing optical
excitation the phase transition is achieved showing a second order character in
contrast to the first order behavior in thermal equilibrium.

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The categories of this paper are: chao-dyn
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The categories of this paper are: bayes-an
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The categories of this paper are: math-ph
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The categories of this paper are: solv-int
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The categories of this paper are: hep-lat
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The categories of this paper are: econ
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The categories of this paper are: eess
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The categories of this paper are: gr-qc
8
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: hep-th
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The categories of this paper are: dg-ga
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The categories of this paper are: stat
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The categories of this paper are: quant-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: adap-org