Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Thermal Green Functions at Zero Energy   The thermal expectation values of all possible bosonic generalised retarded
functions evaluated at zero energy are studied. The relationship of such
functions to calculational schemes, technical problems and physical
applications is outlined. It is then shown that all generalised retarded
functions constructed from any one set of bosonic fields are equal at zero
energy. This is done completely generally and is not limited to any
approximation scheme such as perturbation theory.

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The categories of this paper are: stat
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The categories of this paper are: patt-sol
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The categories of this paper are: chao-dyn
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The categories of this paper are: mtrl-th
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The categories of this paper are: nucl-th
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The categories of this paper are: astro-ph
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The categories of this paper are: adap-org
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The categories of this paper are: cmp-lg
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The categories of this paper are: cond-mat
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The categories of this paper are: math-ph
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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: dg-ga
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The categories of this paper are: hep-ex
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The categories of this paper are: gr-qc
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The categories of this paper are: acc-phys