Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: A theoretical model obtained in momentum space for charge transport in a
  system consisting of non-interacting polarons
5
The categories of this paper are: gr-qc
36
The categories of this paper are: cmp-lg
3
The categories of this paper are: physics
10
The categories of this paper are: q-bio
22
The categories of this paper are: chao-dyn
21
The categories of this paper are: adap-org
32
The categories of this paper are: atom-ph
15
The categories of this paper are: nucl-ex
12
The categories of this paper are: nucl-th
31
The categories of this paper are: ao-sci
27
The categories of this paper are: comp-gas
6
The categories of this paper are: astro-ph
23
The categories of this paper are: solv-int
29
The categories of this paper are: funct-an
30
The categories of this paper are: q-alg
18
The categories of this paper are: econ