Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Vortex precession in Bose-Einstein condensates: observations with filled
  and empty cores   We have observed and characterized the dynamics of singly quantized vortices
in dilute-gas Bose-Einstein condensates. Our condensates are produced in a
superposition of two internal states of 87Rb, with one state supporting a
vortex and the other filling the vortex core. Subsequently, the state filling
the core can be partially or completely removed, reducing the radius of the
core by as much as a factor of 13, all the way down to its bare value. The
corresponding superfluid rotation rates, evaluated at the core radius, vary by
a factor of 150, but the precession frequency of the vortex core about the
condensate axis changes by only a factor of two.

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The categories of this paper are: hep-ph
16
The categories of this paper are: stat
6
The categories of this paper are: astro-ph
15
The categories of this paper are: nucl-ex
32
The categories of this paper are: atom-ph
18
The categories of this paper are: econ
28
The categories of this paper are: alg-geom
23
The categories of this paper are: solv-int
5
The categories of this paper are: gr-qc
10
The categories of this paper are: q-bio
22
The categories of this paper are: chao-dyn
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The categories of this paper are: nlin
25
The categories of this paper are: patt-sol
29
The categories of this paper are: funct-an
30
The categories of this paper are: q-alg
27
The categories of this paper are: comp-gas