Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Isospin violation in low-energy pion-nucleon scattering revisited   We calculate isospin breaking in pion-nucleon scattering in the threshold
region in the framework of covariant baryon chiral perturbation theory. All
effects due to quark mass differences as well as real and virtual photons are
consistently included. As an application, we discuss the energy dependence of
the triangle relation that connects elastic scattering on the proton pi+- p -->
pi+- p with the charge exchange reaction pi- p --> pi0 n.

21
The categories of this paper are: adap-org
6
The categories of this paper are: astro-ph
17
The categories of this paper are: q-fin
11
The categories of this paper are: hep-lat
9
The categories of this paper are: nlin
10
The categories of this paper are: q-bio
2
The categories of this paper are: math
3
The categories of this paper are: physics
34
The categories of this paper are: chem-ph
15
The categories of this paper are: nucl-ex
14
The categories of this paper are: math-ph
7
The categories of this paper are: hep-th
35
The categories of this paper are: mtrl-th
37
The categories of this paper are: supr-con
27
The categories of this paper are: comp-gas
1
The categories of this paper are: cs