Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Elastic pion-nucleon scattering in chiral perturbation theory: A fresh
  look   Elastic pion-nucleon scattering is analyzed in the framework of chiral
perturbation theory up to fourth order within the heavy-baryon expansion and a
covariant approach based on an extended on-mass-shell renormalization scheme.
We discuss in detail the renormalization of the various low-energy constants
and provide explicit expressions for the relevant $\beta$-functions and the
finite subtractions of the power-counting breaking terms within the covariant
formulation. To estimate the theoretical uncertainty from the truncation of the
chiral expansion, we employ an approach which has been successfully applied in
the most recent analysis of the nuclear forces. This allows us to reliably
extract the relevant low-energy constants from the available scattering data at
low energy. The obtained results provide a clear evidence that the breakdown
scale of the chiral expansion for this reaction is related to the
$\Delta$-resonance. The explicit inclusion of the leading contributions of the
$\Delta$-isobar is demonstrated to substantially increase the range of
applicability of the effective field theory. The resulting predictions for the
phase shifts are in an excellent agreement with the ones from the recent
Roy-Steiner-equation analysis of pion-nucleon scattering.

29
The categories of this paper are: funct-an
18
The categories of this paper are: econ
0
The categories of this paper are: hep-ph
8
The categories of this paper are: hep-ex
32
The categories of this paper are: atom-ph
26
The categories of this paper are: bayes-an
14
The categories of this paper are: math-ph
36
The categories of this paper are: cmp-lg
11
The categories of this paper are: hep-lat
3
The categories of this paper are: physics
24
The categories of this paper are: dg-ga
31
The categories of this paper are: ao-sci
27
The categories of this paper are: comp-gas
20
The categories of this paper are: acc-phys
28
The categories of this paper are: alg-geom
34
The categories of this paper are: chem-ph