Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Galactic Positron Excess from Selectively Enhanced Dark Matter
  Annihilation   Precision measurements of the positron flux in cosmic ray have revealed an
unexplained bump in the spectrum around $E\simeq 300\,\mathrm{GeV}$, not
clearly attributable to known astrophysical processes. We propose annihilation
of dark matter of mass $m_\chi = 780\,\mathrm{GeV}$ with a late-time cross
section $\sigma v = 4.63\times 10^{-24}\,\mathrm{cm^3\,s^{-1}}$ as a possible
source. The nonmonotonic dependence of the annihilation rate on dark matter
velocity, owing to a selective $p$-wave Sommerfeld enhancement, allows such a
large signal from the Milky Way without violating corresponding constraints
from CMB and dwarf galaxy observations. We briefly explore other signatures of
this scenario, and outline avenues to test it in future experiments.

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The categories of this paper are: eess
7
The categories of this paper are: hep-th
1
The categories of this paper are: cs
2
The categories of this paper are: math
34
The categories of this paper are: chem-ph
24
The categories of this paper are: dg-ga
25
The categories of this paper are: patt-sol
21
The categories of this paper are: adap-org
13
The categories of this paper are: quant-ph
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The categories of this paper are: q-fin
3
The categories of this paper are: physics
27
The categories of this paper are: comp-gas
20
The categories of this paper are: acc-phys
15
The categories of this paper are: nucl-ex
30
The categories of this paper are: q-alg
16
The categories of this paper are: stat