Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Calculation of Universal Amplitude Ratios in three-loop order   For the universality class of three-dimensional Ising systems the ratio of
the high- and low-temperature amplitudes for the correlation length and for the
susceptibility are universal quantities. They can be calculated by renormalized
perturbation theory for scalar $\phi^4$ theory in fixed dimensions $D=3$ in the
symmetric phase and in the phase of broken symmetry. In this article the
amplitude ratios are calculated in the three-loop approximation. Using the
fixed point values of the coupling constants we obtain $f_+/f_-=2.013(28)$ and
$C_+/C_-=4.72(17)$.

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The categories of this paper are: atom-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: funct-an
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The categories of this paper are: nlin
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The categories of this paper are: solv-int
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The categories of this paper are: q-fin
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The categories of this paper are: hep-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: eess
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The categories of this paper are: gr-qc
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The categories of this paper are: comp-gas
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The categories of this paper are: q-alg
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The categories of this paper are: mtrl-th
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The categories of this paper are: hep-th
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The categories of this paper are: supr-con
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The categories of this paper are: astro-ph