Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Surface Region of Superfluid Helium as an Inhomogeneous Bose-Condensed
  Gas   We present arguments that the low density surface region of self-bounded
superfluid $^4$He systems is an inhomogeneous dilute Bose gas, with almost all
of the atoms occupying the same single-particle state at $T = 0$. Numerical
evidence for this complete Bose-Einstein condensation was first given by the
many-body variational calculations of $^4$He droplets by Lewart, Pandharipande
and Pieper in 1988. We show that the low density surface region can be treated
rigorously using a generalized Gross-Pitaevskii equation for the Bose order
parameter.

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The categories of this paper are: math
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The categories of this paper are: eess
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The categories of this paper are: patt-sol
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The categories of this paper are: nlin
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The categories of this paper are: physics
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The categories of this paper are: hep-th
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-ex
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The categories of this paper are: q-bio
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The categories of this paper are: plasm-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: adap-org
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The categories of this paper are: math-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: cs
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The categories of this paper are: gr-qc