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arXiv · 1704.08988

Elastic and inelastic pion-nucleon scattering to fourth order in chiral perturbation theory

D. Siemens·V. Bernard·E. Epelbaum·A. M. Gasparyan·H. Krebs·Ulf-G. Meißner
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Abstract

We extend our previous study of elastic pion-nucleon scattering in the framework of chiral perturbation theory by performing a combined analysis of the reactions $\pi N \to \pi N$ and $\pi N \to \pi \pi N$. The calculation is carried out to fourth order in the chiral expansion using the heavy baryon approach and the covariant formulation supplemented with a modified version of the extended on-mass-shell renormalization scheme. We demonstrate that a combined fit to experimental data in both channels leads to a reduced amount of correlations between the low-energy constants. A satisfactory description of the experimental data in both channels is obtained, which is further improved upon including tree-level contributions of the $\Delta$(1232) resonance. We also explore a possibility of using the empirical information about $\pi N$ subthreshold parameters obtained recently by means of the Roy-Steiner equations to stabilize the fits.

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D. Siemens, V. Bernard, E. Epelbaum, A. M. Gasparyan, H. Krebs, Ulf-G. Meißner. 2017-04-28. Elastic and inelastic pion-nucleon scattering to fourth order in chiral perturbation theory. https://doi.org/10.1103/physrevc.96.055205

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