NN-->NNpi from the effective field theory point of view: short comings and gains

Abstract

Based on a counting scheme for the application of chiral perturbation theory to pion production in NN collisions p-wave production is studied. It is demonstrated that, contrary to the s-wave production where loops enter at too low an order to allow the scheme predictive power, there are certain p-wave observables where parameter free predictions are possible. These predictions are consistent with experimental data. We show that the investigation of charged pion production yields a constraint on a contribution to the three-nucleon force with a spin-isospin structure that could resolve the $A_y$ puzzle in $nd$ scattering.