Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Phase structure of neutron $^{3}P_{2}$ superfluids in strong magnetic
  fields in neutron stars   We discuss the effect of a strong magnetic field on neutron $^{3}P_{2}$
superfluidity. Based on the attraction in the $^{3}P_{2}$ pair of two neutrons,
we derive the Ginzburg-Landau equation in the path-integral formalism by
adopting the bosonization technique and leave the next-to-leading order in the
expansion of the magnetic field $B$. We determine the $(T,B)$ phase diagram
with temperature $T$, comprising three phases: the uniaxial nematic (UN) phase
for $B=0$, D$_{2}$-biaxial nematic (BN) and D$_{4}$-BN phases in finite $B$ and
strong $B$ such as magnetars, respectively, where D$_{2}$ and D$_{4}$ are
dihedral groups. We find that, compared with the leading order in the magnetic
field known before, the region of the D$_{2}$-BN phase in the $(T,B)$ plane is
extended by the effect of the next-to-leading-order terms of the magnetic
field. We also present the thermodynamic properties, such as heat capacities
and spin susceptibility, and find that the spin susceptibility exhibits
anisotropies in the UN, D$_{2}$-BN, and D$_{4}$-BN phases. This information
will be useful to understand the internal structures of magnetars.

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The categories of this paper are: plasm-ph
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The categories of this paper are: eess
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The categories of this paper are: hep-th
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The categories of this paper are: math
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The categories of this paper are: econ
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The categories of this paper are: adap-org
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The categories of this paper are: comp-gas
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The categories of this paper are: ao-sci
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The categories of this paper are: funct-an
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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-lat
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The categories of this paper are: alg-geom
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The categories of this paper are: gr-qc
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The categories of this paper are: chem-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: atom-ph