Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Chiral Perturbation Theory and Nuclear Physics   Chiral symmetry serves as a guiding principle in low-energy hadron dynamics.
An effective lagrangian, which explicitly breaks chiral symmetry via a small
mass term, allows for a systematic method of calculating higher order
corrections to tree-level results. This is applied to radiative muon capture on
hydrogen, %to extract the weak pseudoscalar form factor, and to proton-proton
$\pi^0$ production near threshold. Both processes pose theoretical challenges
in light of recent experimental results.

5
The categories of this paper are: gr-qc
27
The categories of this paper are: comp-gas
21
The categories of this paper are: adap-org
4
The categories of this paper are: cond-mat
26
The categories of this paper are: bayes-an
37
The categories of this paper are: supr-con
11
The categories of this paper are: hep-lat
13
The categories of this paper are: quant-ph
6
The categories of this paper are: astro-ph
2
The categories of this paper are: math
14
The categories of this paper are: math-ph
3
The categories of this paper are: physics
19
The categories of this paper are: eess
34
The categories of this paper are: chem-ph
9
The categories of this paper are: nlin
22
The categories of this paper are: chao-dyn