Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Neutron charge radius and the Dirac equation   We consider the Dirac equation for a finite-size neutron in an external
electric field. We explicitly incorporate Dirac-Pauli form factors into the
Dirac equation. After a non-relativistic reduction, the Darwin-Foldy term is
cancelled by a contribution from the Dirac form factor, so that the only
coefficient of the external field charge density is $e/6 r^2_{En}$, i. e. the
root mean square radius associated with the electric Sachs form factor . Our
result is similar to a recent result of Isgur, and reconciles two apparently
conflicting viewpoints about the use of the Dirac equation for the description
of nucleons.

34
The categories of this paper are: chem-ph
28
The categories of this paper are: alg-geom
13
The categories of this paper are: quant-ph
11
The categories of this paper are: hep-lat
24
The categories of this paper are: dg-ga
19
The categories of this paper are: eess
9
The categories of this paper are: nlin
8
The categories of this paper are: hep-ex
22
The categories of this paper are: chao-dyn
26
The categories of this paper are: bayes-an
27
The categories of this paper are: comp-gas
33
The categories of this paper are: plasm-ph
6
The categories of this paper are: astro-ph
17
The categories of this paper are: q-fin
1
The categories of this paper are: cs
16
The categories of this paper are: stat