N. Fettes et Ug. Meissner, Complete analysis of pion-nucleon scattering in chiral perturbation theoryto third order, NUCL PHYS A, 693(3-4), 2001, pp. 693-709
We consider pion-nucleon scattering in heavy-baryon chiral perturbation the
ory to third order. All electromagnetic corrections appearing to this order
are included. We thus have a consistent description of strong and electrom
agnetic effects, which allows us to isolate the strong part of the interact
ion in an unambiguous way. We give pion-nucleon phase shifts up to pion lab
oratory momenta of 100 MeV and find sizeable differences for the S-waves of
the elastic channels compared to previous phase-shift analyses. The precis
e description of the scattering process also allows us to address the quest
ion of isospin violation in the strong interaction. For the usually employe
d triangle relation we find an isospin-breaking effect of -0.7% in the S-wa
ve. (C) 2001 Elsevier Science B.V. All rights reserved.