Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: A new way to explain the 511 keV signal from the center of the Galaxy
  and its possible consequences
23
The categories of this paper are: solv-int
25
The categories of this paper are: patt-sol
0
The categories of this paper are: hep-ph
10
The categories of this paper are: q-bio
1
The categories of this paper are: cs
28
The categories of this paper are: alg-geom
15
The categories of this paper are: nucl-ex
24
The categories of this paper are: dg-ga
7
The categories of this paper are: hep-th
36
The categories of this paper are: cmp-lg
31
The categories of this paper are: ao-sci
17
The categories of this paper are: q-fin
35
The categories of this paper are: mtrl-th
16
The categories of this paper are: stat
18
The categories of this paper are: econ
20
The categories of this paper are: acc-phys