Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Thermodynamics and Superradiant Phase Transitions in a three-level Dicke
  Model   We analyse the thermodynamic properties of a generalised Dicke model, i.e. a
collection of three-level systems interacting with two bosonic modes. We show
that at finite temperatures the system undergoes first-order phase transitions
only, which is in contrast to the zero-temperature case where a second-order
phase transition exist as well. We discuss the free energy and prominent
expectation values. The limit of vanishing temperature is discussed as well.

29
The categories of this paper are: funct-an
34
The categories of this paper are: chem-ph
0
The categories of this paper are: hep-ph
32
The categories of this paper are: atom-ph
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The categories of this paper are: dg-ga
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
33
The categories of this paper are: plasm-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-lat
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The categories of this paper are: q-fin
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The categories of this paper are: math-ph
30
The categories of this paper are: q-alg
2
The categories of this paper are: math