Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ultrahigh-energy diffuse gamma-ray emission from cosmic-ray interactions
  with medium surrounding acceleration sources   The diffuse $\gamma$-ray spectrum at sub-PeV energy region has been measured
for the first time by the Tibet-AS$\gamma$ experiment. It will shed new light
on the understanding of origin and propagation of Galactic cosmic rays at very
high energies. It has been pointed out that the traditional cosmic ray
propagation model based on low energy measurements undershoot the new data, and
modifications of the model with new ingredients or alternative propagation
framework is required. In this work, we propose that the hadronic interactions
between freshly accelerated cosmic rays and the medium surrounding the sources,
which was neglected in the traditional model, can naturally account for the
Tibet-AS$\gamma$ diffuse emission. We show that this scenario gives a
consistent description of other secondary species such as the positron
spectrum, the boron-to-carbon ratio, and the antiproton-to-proton ratio. As a
result, the electron spectrum above 10 TeV will have a hardening due to this
secondary component, which may be tested by future measurements.

7
The categories of this paper are: hep-th
1
The categories of this paper are: cs
30
The categories of this paper are: q-alg
3
The categories of this paper are: physics
20
The categories of this paper are: acc-phys
33
The categories of this paper are: plasm-ph
26
The categories of this paper are: bayes-an
2
The categories of this paper are: math
27
The categories of this paper are: comp-gas
11
The categories of this paper are: hep-lat
5
The categories of this paper are: gr-qc
9
The categories of this paper are: nlin
16
The categories of this paper are: stat
10
The categories of this paper are: q-bio
0
The categories of this paper are: hep-ph
15
The categories of this paper are: nucl-ex