Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Construction of gauge invariant effective nucleonic theories: functional
  approach   Starting from relativistic quantum field theories, describing interacting
nucleons and pions coupled to the dynamical electromagnetic field, the pion
degrees of freedom are eliminated by means of functional integration. Apart
from taking into account some operators perturbatively in $e$, e.g. the vacuum
polarization, this procedure is exact, giving effective theories for nucleons
and photons. The subsequent nonrelativistic reduction yields the corresponding
nonrelativistic quantum field theory. The latter is unique, irrespective of the
precize form of the original nucleon-pion interaction. Nucleonic potentials and
electromagnetic interactions are mutually consistent. Local gauge invariance is
satisfied at any stage of the formal developments.

24
The categories of this paper are: dg-ga
20
The categories of this paper are: acc-phys
16
The categories of this paper are: stat
28
The categories of this paper are: alg-geom
18
The categories of this paper are: econ
29
The categories of this paper are: funct-an
31
The categories of this paper are: ao-sci
14
The categories of this paper are: math-ph
15
The categories of this paper are: nucl-ex
6
The categories of this paper are: astro-ph
8
The categories of this paper are: hep-ex
26
The categories of this paper are: bayes-an
27
The categories of this paper are: comp-gas
32
The categories of this paper are: atom-ph
30
The categories of this paper are: q-alg
10
The categories of this paper are: q-bio