Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nonlinear spin diffusion and spin rotation in a trapped Fermi gas   Transverse spin diffusion in a polarized, interacting Fermi gas leads to the
Leggett-Rice effect, where the spin current precesses around the local
magnetization. With a spin-echo sequence both the transverse diffusivity and
the spin-rotation parameter $\gamma$ are obtained; the sign of $\gamma$ reveals
the repulsive or attractive character of the effective interaction. In a
trapped Fermi gas the spin diffusion equations become nonlinear, and their
numerical solution exhibits an inhomogeneous spin state even at the spin echo
time. While the microscopic diffusivity and $\gamma$ increase at weak coupling,
their apparent values inferred from the trap-averaged magnetization saturate in
agreement with a recent experiment for a dilute ultracold Fermi gas.

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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: dg-ga
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The categories of this paper are: nlin
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The categories of this paper are: hep-ex
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The categories of this paper are: cs
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The categories of this paper are: mtrl-th
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The categories of this paper are: solv-int
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The categories of this paper are: chao-dyn
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The categories of this paper are: physics
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The categories of this paper are: econ
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The categories of this paper are: gr-qc
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The categories of this paper are: hep-lat
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The categories of this paper are: hep-th
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The categories of this paper are: hep-ph
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The categories of this paper are: funct-an