Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Proton-proton bremsstrahlung below and above pion-threshold: the
  influence of the $\Delta$-isobar   The proton-proton bremsstrahlung is investigated within a coupled-channel
model with the $\Delta$ degree of freedom. The model is consistent with the
$NN$ scattering up to 1 GeV and the $\gamma N\Delta$ vertex determined in the
study of pion photoproduction reactions. It is found that the $\Delta$
excitation can significantly improve the agreements with the $pp \rightarrow
pp\gamma$ at $E_{lab}=280$ MeV. Predictions at $E_{lab}=550$ and $800$ MeV are
presented for future experimental tests.

17
The categories of this paper are: q-fin
28
The categories of this paper are: alg-geom
33
The categories of this paper are: plasm-ph
26
The categories of this paper are: bayes-an
8
The categories of this paper are: hep-ex
23
The categories of this paper are: solv-int
3
The categories of this paper are: physics
11
The categories of this paper are: hep-lat
16
The categories of this paper are: stat
2
The categories of this paper are: math
32
The categories of this paper are: atom-ph
6
The categories of this paper are: astro-ph
13
The categories of this paper are: quant-ph
20
The categories of this paper are: acc-phys
7
The categories of this paper are: hep-th
34
The categories of this paper are: chem-ph