Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Gauge (non-)invariant Green functions of Dirac fermions coupled to gauge
  fields
37
The categories of this paper are: supr-con
36
The categories of this paper are: cmp-lg
33
The categories of this paper are: plasm-ph
1
The categories of this paper are: cs
15
The categories of this paper are: nucl-ex
29
The categories of this paper are: funct-an
25
The categories of this paper are: patt-sol
21
The categories of this paper are: adap-org
12
The categories of this paper are: nucl-th
22
The categories of this paper are: chao-dyn
9
The categories of this paper are: nlin
18
The categories of this paper are: econ
11
The categories of this paper are: hep-lat
17
The categories of this paper are: q-fin
13
The categories of this paper are: quant-ph
26
The categories of this paper are: bayes-an