Semi-relativistic approach to NN scattering in baryon chiral perturbation theory

We consider a new approach to the nucleon-nucleon scattering problem in the framework of the higher-derivative formulation of baryon chiral perturbation theory. Starting with a Lorentz-invariant form of the effective Lagrangian we work out a new framework where the leading-order amplitude is calculated by solving renormalized equations and corrections are taken into account perturbatively. Analogously to the KSW approach, all divergences to any finite order are absorbed in the redefinition of a finite number of parameters of the effective potential at given order. On the other hand, analogously to Weinberg's power counting, the one-pion-exchange potential is of leading order and is treated non-perturbatively. The suggested approach preserves all underlying symmetries (to a given order of accuracy) and makes the self-consistency of the power counting explicit. (orig.)