Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Dark Radiation from a hidden U(1)
35
The categories of this paper are: mtrl-th
20
The categories of this paper are: acc-phys
16
The categories of this paper are: stat
31
The categories of this paper are: ao-sci
15
The categories of this paper are: nucl-ex
32
The categories of this paper are: atom-ph
1
The categories of this paper are: cs
3
The categories of this paper are: physics
30
The categories of this paper are: q-alg
6
The categories of this paper are: astro-ph
23
The categories of this paper are: solv-int
14
The categories of this paper are: math-ph
34
The categories of this paper are: chem-ph
22
The categories of this paper are: chao-dyn
7
The categories of this paper are: hep-th
37
The categories of this paper are: supr-con