Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Spectral Density Method Applied to the Hot Quantum Field Theories   The spectral density method being applied to the quantum field theory at
finite temperature is revived and its possibilities are briefly discussed.

25
The categories of this paper are: patt-sol
36
The categories of this paper are: cmp-lg
8
The categories of this paper are: hep-ex
5
The categories of this paper are: gr-qc
24
The categories of this paper are: dg-ga
10
The categories of this paper are: q-bio
26
The categories of this paper are: bayes-an
17
The categories of this paper are: q-fin
3
The categories of this paper are: physics
18
The categories of this paper are: econ
2
The categories of this paper are: math
21
The categories of this paper are: adap-org
27
The categories of this paper are: comp-gas
23
The categories of this paper are: solv-int
6
The categories of this paper are: astro-ph
13
The categories of this paper are: quant-ph