Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Unitary model for the $\gamma p \to \gamma \pi^0 p$ reaction and the
  magnetic dipole moment of the $\Delta^+(1232)$   Radiative pion photoproduction in the $\Delta(1232)$ resonance region is
studied with the aim to access the $\Delta^+(1232)$ magnetic dipole moment. We
present a unitary model of the $\gamma p \to \gamma \pi N$ ($\pi N = \pi^0 p,
\pi^+ n$) reactions, where the $\pi N$ rescattering is included in an on-shell
approximation. In this model, the low energy theorem which couples the $\gamma
p \to \gamma \pi N$ process in the limit of a soft final photon to the $\gamma
p \to \pi N$ process is exactly satisfied. We study the sensitivity of the
$\gamma p \to \gamma \pi^0 p$ process at higher values of the final photon
energy to the $\Delta^+(1232)$ magnetic dipole moment. We compare our results
with existing data and give predictions for forthcoming measurements of angular
and energy distributions. It is found that the photon asymmetry and a helicity
cross section are particularly sensitive to the $\Delta^+$ magnetic dipole
moment.

14
The categories of this paper are: math-ph
2
The categories of this paper are: math
37
The categories of this paper are: supr-con
17
The categories of this paper are: q-fin
35
The categories of this paper are: mtrl-th
1
The categories of this paper are: cs
30
The categories of this paper are: q-alg
24
The categories of this paper are: dg-ga
22
The categories of this paper are: chao-dyn
13
The categories of this paper are: quant-ph
19
The categories of this paper are: eess
3
The categories of this paper are: physics
33
The categories of this paper are: plasm-ph
34
The categories of this paper are: chem-ph
31
The categories of this paper are: ao-sci
20
The categories of this paper are: acc-phys