Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Transport coefficients in Chiral Perturbation Theory   We present recent results on the calculation of transport coefficients for a
pion gas at zero chemical potential in Chiral Perturbation Theory using Linear
Response Theory. More precisely, we show the behavior of DC conductivity and
shear viscosity at low temperatures. To compute transport coefficients, the
standard power counting of ChPT has to be modified. The effects derived from
imposing unitarity are also analyzed. As physical applications in Relativistic
Heavy Ion Collisions, we show the relation of the DC conductivity to
soft-photon production and phenomenological effects related to a nonzero shear
viscosity. In addition, our values for the shear viscosity to entropy ratio
satisfy the KSS bound.

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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: dg-ga
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The categories of this paper are: ao-sci
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The categories of this paper are: math-ph
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The categories of this paper are: physics
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The categories of this paper are: quant-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: plasm-ph
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The categories of this paper are: gr-qc
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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: stat
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The categories of this paper are: q-alg
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The categories of this paper are: eess
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The categories of this paper are: patt-sol