Abstract

We apply the perturbative chiral quark model to give predictions for the electromagnetic O (p(2)) low-energy couplings of the ChPT effective Lagrangian that define the electromagnetic mass shifts of nucleons and first-order (e(2)) radiative corrections to the piN scattering amplitude. 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. (C) 2001 Elsevier Science B.V. All rights reserved.