Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The creation of two-dimensional composite solitons in spin-orbit-coupled
  self-attractive Bose-Einstein condensates in free space   It is commonly known that two-dimensional mean-field models of optical and
matter waves with the cubic self-attraction cannot produce stable solitons in
free space because of the occurrence of the collapse in the same setting. By
means of the numerical analysis and variational approximation, we demonstrate
that the two-component model of the Bose-Einstein condensate, with the
spin-orbit Rashba coupling and cubic attractive interactions, gives rise to
solitary-vortex complexes of two types: semi-vortices (SVs, with a vortex in
one component and a fundamental soliton in the other), and mixed modes (MMs,
with topological charges 0 and +1/-1 mixed in both components). These two-
dimensional composite modes can be created using the trapping
harmonic-oscillator (HO) potential, but remain stable in the free space, if the
trap is gradually removed. The SVs and MMs realize the ground state of the
system, provided that the self-attraction in the two components is,
respectively, stronger or weaker than the cross-attraction between them. The
SVs and MMs which are not the ground state are subject to a drift instability.
In the free space (in the absence of the HO trap), modes of both types
degenerate into unstable Townes solitons when their norms attain the respective
critical values, while there is no lower existence threshold for the stable
modes. Moving free-space stable solitons are also found in the present
non-Galilean-invariant system, up to a critical velocity. Collisions between
two moving solitons lead to their merger into a single one.

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The categories of this paper are: alg-geom
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The categories of this paper are: math-ph
8
The categories of this paper are: hep-ex
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The categories of this paper are: q-fin
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The categories of this paper are: q-alg
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The categories of this paper are: supr-con
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The categories of this paper are: plasm-ph
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The categories of this paper are: stat
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The categories of this paper are: quant-ph
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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: comp-gas
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The categories of this paper are: math
0
The categories of this paper are: hep-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: eess