Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Coordinate-space approach to vacuum polarization   The vacuum-polarization correction for bound electrons or muons is examined.
The objective is to formulate a framework for calculating the correction from
bound-state quantum electrodynamics entirely in coordinate space, including the
Uehling potential which is usually isolated and treated separately.
Pauli-Villars regularization is applied to the coordinate-space calculation and
the most singular terms are shown to be eliminated, leaving the physical
correction after charge renormalization. The conventional derivation of the
Uehling potential in momentum space is reviewed and compared to the
coordinate-space derivation.

25
The categories of this paper are: patt-sol
6
The categories of this paper are: astro-ph
33
The categories of this paper are: plasm-ph
18
The categories of this paper are: econ
23
The categories of this paper are: solv-int
27
The categories of this paper are: comp-gas
15
The categories of this paper are: nucl-ex
17
The categories of this paper are: q-fin
2
The categories of this paper are: math
26
The categories of this paper are: bayes-an
10
The categories of this paper are: q-bio
19
The categories of this paper are: eess
5
The categories of this paper are: gr-qc
32
The categories of this paper are: atom-ph
36
The categories of this paper are: cmp-lg
37
The categories of this paper are: supr-con