https://doi.org/10.1140/epjc/s10052-015-3728-7
Regular Article - Theoretical Physics
Baryon chiral perturbation theory extended beyond the low-energy region
1
Institut für Theoretische Physik II, Ruhr-Universität Bochum, 44780, Bochum, Germany
2
Institute for Advanced Simulation, Institut für Kernphysik and Jülich Center for Hadron Physics, Forschungszentrum Jülich, 52425, Jülich, Germany
3
Tbilisi State University, 0186, Tbilisi, Georgia
4
Helmholtz Institut für Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Universität Bonn, 53115, Bonn, Germany
* e-mail: jgegelia@hotmail.com
Received:
30
July
2015
Accepted:
8
October
2015
Published online:
22
October
2015
We consider an extension of the one-nucleon sector of baryon chiral perturbation theory beyond the low-energy region. The applicability of this approach for higher energies is restricted to small scattering angles, i.e. the kinematical region, where the quark structure of hadrons cannot be resolved. The main idea is to re-arrange the low-energy effective Lagrangian according to a new power counting and to exploit the freedom of the choice of the renormalization condition for loop diagrams. We generalize the extended on-mass-shell scheme for the one-nucleon sector of baryon chiral perturbation theory by choosing a sliding scale, that is, we expand the physical amplitudes around kinematical points beyond the threshold. This requires the introduction of complex-valued renormalized coupling constants, which can be either extracted from experimental data, or calculated using the renormalization group evolution of coupling constants fixed in threshold region.
© SIF and Springer-Verlag Berlin Heidelberg, 2015
