Abstract

We apply the perturbative chiral quark model to the study of the low-energy piN interaction. Using an effective chiral Lagrangian we reproduce the Weinberg-Tomozawa result for the S-wave piN scattering lengths. After inclusion of the photon field we give predictions for the electromagnetic O(p(2)) low-energy couplings of the chiral perturbation theory effective Lagrangian that define the electromagnetic mass shifts of nucleons and first-order (e(2)) radiative corrections to the piN scattering amplitude. Finally, we estimate the leading isospin-breaking correction to the strong energy shift of the pi(-)p atom in the 1s state, which is relevant for the experiment "pionic hydrogen" at PSI.