Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Current conservation, screening and the magnetic moment of the $\Delta$
  resonance. -- 1. Formulation without quark degrees of freedom   The pion-nucleon bremsstrahlung $\pi+N\Longrightarrow\gamma'+\pi'+N'$ is
studied in a new form of current conservation. According to this condition, the
internal and external particle radiation parts of the $\pi N$ radiation
amplitude have opposite signs, i.e., they contain terms which must cancel each
other.
  Therefore, one has a screening of the internal and external particle
radiation in the $\pi N$ bremsstrahlung. In particular, it is shown that the
double $\Delta$ exchange diagram with the $\Delta-\gamma' \Delta'$ vertex
cancel against the appropriate longitudinal part of the external particle
radiation diagrams. Consequently, a model independent relation between the
magnetic dipole moments of the $\Delta^+$ and $\Delta^{++}$ resonances and the
anomalous magnetic moment of the proton $\mu_p$ is obtained, where
$\mu_{\Delta}$ is expressed by $\mu_p$ as $\mu_{\Delta^+}={{M_{\Delta}}\over
{m_p}} \mu_p$ and $\mu_{\Delta^{++}}={3\over 2}\mu_{\Delta^+}$ in agreement
with the values extracted from the fit for the experimental cross section of
the $\pi^+ p\to\gamma'\pi^+ p$ reaction.

17
The categories of this paper are: q-fin
9
The categories of this paper are: nlin
1
The categories of this paper are: cs
32
The categories of this paper are: atom-ph
8
The categories of this paper are: hep-ex
4
The categories of this paper are: cond-mat
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
13
The categories of this paper are: quant-ph
7
The categories of this paper are: hep-th
36
The categories of this paper are: cmp-lg
28
The categories of this paper are: alg-geom
26
The categories of this paper are: bayes-an
29
The categories of this paper are: funct-an
33
The categories of this paper are: plasm-ph