Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Acoustics of tachyon Fermi gas   We consider a Fermi gas of free tachyons as a continuous medium and find
whether it satisfies the causality condition. There is no stable tachyon matter
with the particle density below critical value $n_T$ and the Fermi momentum
$k_F<\sqrt{\frac 32}m$ that depends on the tachyon mass $m$. The pressure $P$
and energy density $E$ cannot be arbitrary small, but the situation $P>E$ is
not forbidden. Existence of shock waves in tachyon gas is also discussed. At
low density $n_T<n<3.45n_T$ the tachyon matter remains stable but no shock wave
do survive.

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The categories of this paper are: q-fin
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The categories of this paper are: physics
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The categories of this paper are: acc-phys
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The categories of this paper are: cond-mat
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The categories of this paper are: gr-qc
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The categories of this paper are: nucl-ex
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The categories of this paper are: cs
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The categories of this paper are: alg-geom
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The categories of this paper are: funct-an
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The categories of this paper are: nucl-th
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The categories of this paper are: math
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The categories of this paper are: comp-gas
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The categories of this paper are: supr-con
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The categories of this paper are: math-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: patt-sol