Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Collective Excitations of Harmonically Trapped Ideal Gases   We theoretically study the collective excitations of an ideal gas confined in
an isotropic harmonic trap. We give an exact solution to the Boltzmann-Vlasov
equation; as expected for a single-component system, the associated mode
frequencies are integer multiples of the trapping frequency. We show that the
expressions found by the scaling ansatz method are a special case of our
solution. Our findings, however, are most useful in case the trap contains more
than one phase: we demonstrate how to obtain the oscillation frequencies in
case an interface is present between the ideal gas and a different phase.

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The categories of this paper are: patt-sol
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The categories of this paper are: alg-geom
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The categories of this paper are: gr-qc
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The categories of this paper are: eess
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The categories of this paper are: hep-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: dg-ga
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The categories of this paper are: solv-int
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The categories of this paper are: chem-ph
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The categories of this paper are: econ
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The categories of this paper are: cs
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The categories of this paper are: hep-th
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The categories of this paper are: acc-phys
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The categories of this paper are: supr-con
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The categories of this paper are: bayes-an
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The categories of this paper are: stat