The Seventh International Symposium on Chiral Symmetry in Hadrons and Nuclei

Starting from hyperbolic dispersion relations for the invariant amplitudes of pion–nucleon scattering together with crossing symmetry and unitarity, we derive a closed system of integral equations for the partial waves of both the s-channel (\pi N->\pi N) and the t-channel (\pi\pi→\bar N N) reaction, called Roy–Steiner equations. We also solve the t-channel subsystem by means of Muskhelishvili–Omnès techniques and present preliminary results on the solution of the s-channel problem.