Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Improved description of the $\pi N$-scattering phenomenology in
  covariant baryon chiral perturbation theory   We present a novel analysis of the $\pi N$ scattering amplitude in covariant
baryon chiral perturbation theory up to ${\cal O}(p^3)$ within the
extended-on-mass-shell renormalization scheme and including the $\Delta(1232)$
explicitly in the $\delta$-counting. We take the hadronic phase shifts provided
by partial wave analyses as basic experimental information to fix the
low-energy constants. Subsequently, we study in detail the various observables
and low-energy theorems related to the $\pi N$ scattering amplitude. In
particular, we discuss the results and chiral expansion of the phase shifts,
the threshold coefficients, the Goldberger-Treiman relation, the pion-nucleon
sigma term and the extrapolation onto the subthreshold region. The chiral
representation of the amplitude in the theory with the $\Delta$ presents a good
convergence from very low energies in the subthreshold region up to energies
well above threshold, leading also to a phenomenological description perfectly
consistent with the one reported by the respective partial wave analyses and
independent determinations. We conclude that a model-independent and systematic
framework to analyze $\pi N$-scattering observables using directly experimental
data shall be possible in covariant baryon chiral perturbation theory.

10
The categories of this paper are: q-bio
26
The categories of this paper are: bayes-an
1
The categories of this paper are: cs
14
The categories of this paper are: math-ph
3
The categories of this paper are: physics
18
The categories of this paper are: econ
7
The categories of this paper are: hep-th
17
The categories of this paper are: q-fin
8
The categories of this paper are: hep-ex
30
The categories of this paper are: q-alg
2
The categories of this paper are: math
23
The categories of this paper are: solv-int
22
The categories of this paper are: chao-dyn
6
The categories of this paper are: astro-ph
16
The categories of this paper are: stat
27
The categories of this paper are: comp-gas